Dial Peer Configuration on Voice Gateway Routers, Cisco IOS

Dial Peer Configuration on Voice Gateway Routers, Cisco IOS
Dial Peer Configuration on Voice
Gateway Routers, Cisco IOS Release
12.4T
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CONTENTS
Dial Peer Overview 1
Finding Feature Information 1
Call Legs 1
POTS Dial Peers 4
Voice-Network Dial Peers 4
Data Dial Peers 5
Creating a Dial Peer Configuration Table 5
Codecs 7
Clear Channel (G.Clear) Codec 8
Adaptive Differential PCM Voice Codec G.726 8
iLBC Codec 8
Toll Fraud Prevention 9
Dial Planning 11
Finding Feature Information 11
Fixed-Length Dial Plans 11
Variable-Length Dial Plans 12
Dial Peer Features and Configuration 15
Finding Feature Information 15
Common Practices 15
Voice Ports 16
Assigning Voice Ports 16
Session Targets 17
Configuring Session Targets 17
Destination Patterns 18
Configuring Destination Patterns 19
Digit Manipulation 20
Wildcards 20
Digit Stripping and Prefixes 22
Forwarding Digits 25
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Contents
Number Expansion 26
Translation Rules 28
CreatingDigitTranslationRules 29
Applying Translation Rules to Inbound POTS Calls 31
Applying Translation Rules to Inbound VoIP Calls 32
Applying Translation Rules to Outbound Call Legs 33
Data Dial Peers 34
Configuring Data Dial Peers 35
Configuring a Search for Dial Peers by Type 35
Inbound and Outbound Dial Peers 36
Matching Inbound Dial Peers 38
Variable-Length Matching 39
Configuring the incoming called-number Command 39
answer-address Command 40
Configuring the destination-pattern Command 41
Configuring the port Command 42
Matching Outbound Dial Peers 42
Using Default Routes 42
Additional Features 43
One Stage and Two Stage Dialing 43
Direct Inward Dialing 44
Configuring Direct Inward Dialing 45
Hunt Groups 46
Configuring Dial Peer Hunting Options 48
Configuring Dial Peer Hunting Options 49
Modem Pass Through 50
Configuring Modem Pass Through Capability for Individual Dial Peers 51
Dual Tone Multifrequency Relay 53
Configuring DTMF Relay and Payload Type 53
Connection PLAR 55
Configuring Connection PLAR 55
Connection PLAR Design Considerations 57
Connection Trunk 57
Configuring Connection Trunk 58
Class of Restrictions 59
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Contents
Verifying Classes of Restrictions 62
Configuring an iLBC Codec 62
Configuring an iLBC Codec on a Dial Peer 62
Troubleshooting Tips 64
What to Do Next 64
Configuring an iLBC Codec in the Voice Class 64
Where to Go for Dial Peer Troubleshooting Information 66
Finding Feature Information 69
Dial Peer Configuration Examples 71
Two Analog Phones 71
Both Connected to the Same Voice Gateway Router 71
Each Connected to Their Own Voice Gateway Routers Using the G.711 Codec 72
Each Connected to Their Own Voice Gateway Routers Using the G.729r8 Codec 73
Two Fax Machines 73
An Analog Phone and an IP Phone Connected over an IP Network 74
Two IP Phones Connected via a Voice over Frame Relay Network 75
Using Digit Manipulation to Overcome the Obstacle of an IP Network Failure 77
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Contents
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Configuring dial peers is the key to implementing dial plans and providing voice services over an IP
packet network. Dial peers are used to identify call source and destination endpoints and to define the
characteristics applied to each call leg in the call connection.
This chapter contains the following sections:
•
•
•
•
•
•
•
•
Finding Feature Information, page 1
Call Legs, page 1
POTS Dial Peers, page 4
Voice-Network Dial Peers, page 4
Data Dial Peers, page 5
Creating a Dial Peer Configuration Table, page 5
Codecs, page 7
Toll Fraud Prevention, page 9
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Call Legs
A traditional voice call over the public switched telephone network (PSTN) uses a dedicated 64K circuit
end to end. In contrast, a voice call over the packet network is made up of discrete segments or call legs. A
call leg is a logical connection between two routers or between a router and a telephony device. A voice
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Call Legs
call comprises four call legs, two from the perspective of the originating router and two from the
perspective of the terminating router, as shown in the figure below.
Figure 1
Dial Peer Call Legs
A dial peer is associated with each call leg. Attributes that are defined in a dial peer and applied to the call
leg include the codec, quality of service (QoS), voice activity detection (VAD), and fax rate. To complete a
voice call, you must configure a dial peer for each of the four call legs in the call connection.
Depending on the call leg, a call is routed using one of the two types of dial peers:
•
•
Plain old telephone system (POTS)--Dial peer that defines the characteristics of a traditional telephony
network connection. POTS dial peers map a dialed string to a specific voice port on the local router,
normally the voice port connecting the router to the local PSTN, PBX, or telephone.
Voice-network--Dial peer that defines the characteristics of a packet network connection. Voicenetwork dial peers map a dialed string to a remote network device, such as the destination router that is
connected to the remote telephony device.
Both POTS and voice-network dial peers are needed to establish voice connections over a packet network.
When a voice call comes into the router, the router must match dial peers to route the call. For inbound
calls from a POTS interface that are being sent over the packet network, the router matches a POTS dial
peer for the inbound call leg and a voice-network dial peer for the outbound call leg. For calls coming into
the router from the packet network, the router matches an outbound POTS dial peer to terminate the call
and an inbound voice-network dial peer for features such as codec, VAD, and QoS.
The figure below shows the call legs and associated dial peers necessary to complete a voice call.
Figure 2
Matching Call Legs to Dial Peers
The following configurations show an example of a call being made from 4085554000 to 3105551000. The
figure below shows the inbound POTS dial peer and the outbound voice over IP (VoIP) dial peer that are
configured on the originating router. The POTS dial peer establishes the source of the call (via the calling
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Call Legs
number or voice port), and the voice-network dial peer establishes the destination by associating the dialed
number with the network address of the remote router.
Figure 3
Dial Peers from the Perspective of the Originating Router
In this example, the dial string 14085554000 maps to telephone number 555-4000, with the digit 1 plus the
area code 408 preceding the number. When you configure the destination pattern, set the string to match the
local dialing conventions.
The figure below shows the inbound VoIP dial peer and outbound POTS dial peer that are configured on
the terminating router to complete the call. Dial peers are of local significance only.
Figure 4
Dial Peers from the Perspective of the Terminating Router
In the previous configuration examples, the last four digits in the VoIP dial peer’s destination pattern were
replaced with wildcards. Which means that from Router A, calling any telephone number that begins with
the digits "1310555" will result in a connection to Router B. This behavior implies that Router B services
all numbers beginning with those digits. From Router B, calling any telephone number that begins with the
digits "1408555" will result in a connection to Router A. This behavior implies that Router A services all
numbers beginning with those digits.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
POTS Dial Peers
Note
It is not always necessary to configure the inbound dial peers. If the router is unable to match a configured
dial peer for the inbound call leg, it uses an internally defined default POTS or voice-network dial peer to
match inbound voice calls. In the example shown in the figure above, dial peer 2 is required only when
making a call from Router B to Router A.
The only exception to the previous example occurs when both POTS dial peers share the same router, as
shown in the figure below. In this circumstance, you do not need to configure a voice-network dial peer.
Figure 5
Communication Between Dial Peers Sharing the Same Router
This type of configuration is similar to the configuration used for hairpinning, which occurs when a voice
call destined for the packet network is instead routed back over the PSTN because the packet network is
unavailable.
POTS Dial Peers
POTS dial peers retain the characteristics of a traditional telephony network connection. POTS dial peers
map a dialed string to a specific voice port on the local router, normally the voice port connecting the router
to the local PSTN, PBX, or telephone.
Voice-Network Dial Peers
Voice-network dial peers are components on an IP network to which a voice gateway router points via the
component’s IP address specified in the session-target command for a particular matching dial peer. The
four types of voice-network dial peers (VoIP, voice over ATM (VoATM), voice over Frame Relay (VoFR),
and multimedia mail over IP (MMoIP)) are determined according to the given packet network technology
and are described as follows:
•
VoIP--Points to the IP address of the destination router that terminates the call.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Data Dial Peers
•
•
•
VoFR--Points to the data-link connection identifier (DLCI) of the interface from which the call exits
the router.
VoATM--Points to the ATM virtual circuit for the interface from which the call exits the router.
MMoIP--Points to the e-mail address of the simple mail transfer protocol (SMTP) server. This type of
dial peer is used only for fax traffic.
Data Dial Peers
Before Cisco IOS Release 12.2(11)T, a Cisco voice gateway would try to match a voice dial peer before
matching and processing a modem call. If a voice dial peer was matched, the call was processed as voice. If
there was no voice dial peer match, only then was a call considered to be a modem call. Voice calls always
received preference over modem calls. Also, there was no way to assign a subset of addresses in the
numbering plan for data calls.
In Cisco IOS Release 12.2(11)T, an interim solution in the form of application called "data_dialpeer" was
introduced to enable gateways to identify dial peers. The application enabled the handling of certain
matched calls as modem calls. Refer to the Fine-Grain Address Segmentation in Dial Peers feature
documentation in Cisco IOS Release 12.2(11)T for more information.
In Cisco IOS Release 12.2(13)T, formal support for data dial peers was released in the form of the DialPeer Support for Data Calls feature, which enables the configuration and order assignment of dial peers so
that the gateway can identify incoming calls as voice or data (modem). You can use the dial-peer data and
dial-peer search commands to perform this configuration. Refer to the "Data Dial Peers" section on page
33 for configuration steps and examples.
Creating a Dial Peer Configuration Table
Before you can configure dial peers, you must obtain specific information about your network. One way to
identify this information is to create a dial peer configuration table. This table should contain all the
telephone numbers and access codes for each router that is carrying telephone traffic in the network.
Because most installations require integrating equipment into an existing voice network, the telephone dial
plans are usually preset.
The figure below shows an example of a network in which Router A, with an IP address of 10.1.1.1,
connects a small sales branch office to the main office through Router B, with an IP address of 10.1.1.2.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Creating a Dial Peer Configuration Table
Note
The example in the figure below shows a VoIP configuration. The same concepts also apply to VoFR and
VoATM applications. The only change is in the format of the session target.
Figure 6
Sample VoIP Network
Three telephone numbers in the sales branch office need dial peers configured for them. Router B is the
primary gateway to the main office; as such, it needs to be connected to the company’s PBX. Four devices
need dial peers, all of which are connected to the PBX, configured for them in the main office.
The table below shows the peer configuration table for the example in the figure above.
Table 1
Dial Peer
Dial Peer Configuration Table for Sample Voice over IP Network
Extension
Prefix
Destination
Pattern
Type
Voice Port
Session
Target
1
51001
5
1408115....
POTS
0:D
--
2
61002
6
1408116....
POTS
0:D
--
3
71003
7
1408117....
POTS
0:D
--
10
--
--
1729555....
VoIP
--
10.1.1.2
1
1000, 1001,
1002, 1003
--
1729555....
POTS
0:D
--
10
--
--
1408.......
VoIP
--
10.1.1.1
Router A
Router B
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Codecs
Codecs
The term codec stands for coder-decoder . A codec is a particular method of transforming analog voice into
a digital bit stream (and vice versa) and also refers to the type of compression used. Several different
codecs have been developed to perform these functions, and each one is known by the number of the
International Telecommunication Union Telecommunication Standardization Sector (ITU-T) standard in
which it is defined. For example, two common codecs are the G.711 and the G.729 codecs.
Codecs use different algorithms to encode analog voice into digital bit streams and have different bit rates,
frame sizes, and coding delays associated with them. Codecs also differ in the amount of perceived voice
quality they achieve. Specialized hardware and software in the digital signal processors (DSPs) perform
codec transformation and compression functions, and different DSPs may offer different selections of
codecs.
Select the same type of codec at both ends of the call. For instance, if a call was coded with a G.729 codec,
it must be decoded with a G.729 codec. Codec choice is configured on dial peers.
The table below lists the H.323, SIP, and MGCP codecs that are supported for voice.
Table 2
Voice Codec/Signaling Support Matrix
Codec
H.323
SIP
MGCP
g711ulaw
Yes
Yes
Yes
g711alaw
Yes
Yes
Yes
g729r81
Yes
Yes
Yes
g729br81
Yes
Yes
Yes
g723ar53
Yes
Yes
Yes
g723ar63
Yes
Yes
Yes
g723r53
Yes
Yes
Yes
g723r63
Yes
Yes
Yes
g726r162
Yes
Yes
Yes
g726r242
Yes
Yes
Yes
g726r32
Yes
Yes
Yes
clear-channel2
Yes
Yes
Yes
iLBC
Yes
Yes
No
For more information, refer to the " Dial Planning " chapter in this document and see the Cisco IOS Voice
Port Configuration Guide.
•
Clear Channel (G.Clear) Codec, page 8
1 Annex A is used in the Cisco platforms that are supported in this software release.
2 For dynamic payload types.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Clear Channel (G.Clear) Codec
Codecs
•
•
Adaptive Differential PCM Voice Codec G.726, page 8
iLBC Codec, page 8
Clear Channel (G.Clear) Codec
G.Clear guarantees bit integrity when transferring a DS-0 through a gateway server, supports the
transporting of nonvoice circuit data sessions through a Voice over IP (VoIP) network, and enables the
VoIP networks to transport ISDN and switched 56 circuit-switched data calls. With the availability of
G.Clear, ISDN data calls that do not require bonding can be supported.
In a transit application, because it is possible to have a mix of voice and data calls, not supporting G.Clear
limits the solution to voice-only calls. The end-user application is in charge of handling packet loss and
error recovery. This packet loss management precludes the use of clear channel with some applications
unless the IP network is carefully engineered.
In an MGCP environment, the voice gateway backhauls the public switched telephony network (PSTN)
signaling channel to the call agent. The call agent examines the bearer capability and determines when a
G.Clear call should be established.
Note
G.Clear codecs cannot be configured on a T1 channel associated signaling (CAS) trunk for incoming
traffic. T1 CAS trunks use least significant bit-robbing for signaling, which causes the data to be incorrect
and re-sent from high level protocols. Traffic on an incoming E1 R2 trunk can be configured.
Adaptive Differential PCM Voice Codec G.726
Adaptive differential pulse code modulation (ADPCM) voice codec operates at bit rates of 16, 24, and 32
kbps. ADPCM provides the following functionality:
•
•
•
Voice mail recording and playback, which is a requirement for Internet voice mail.
Voice transport for cellular, wireless, and cable markets.
High voice quality voice transport at 32 kbps.
iLBC Codec
The internet Low Bitrate Codec (iLBC) Has the following benefits:
•
•
•
•
•
Is designed specifically for packet-based communication.
Is royalty free.
Provides high-voice quality, even in conditions with high-packet loss.
Has a sampling rate of 8 kHz, for narrow band speech.
Supports two fixed bit-rate frame lengths:
•
◦ Bit-rate of 13.3 kbps with an encoding frame length of 30 ms
◦ Bit-rate of 15.2 kbps with an encoding frame length of 20 ms
Is designed to be robust, even with packet loss. iLBC treats each packet independently and recovers
from packet loss on the packet immediately following the lost one. By utilizing the entire available
frequency band, this codec provides a high voice quality.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
Toll Fraud Prevention
Platforms that iLBC Supports
iLBC is supported on Cisco AS5350XM and Cisco AS5400XM Universal Gateways with Voice Feature
Cards (VFCs) and IP-to-IP gateways with no transcoding and conferencing.
Using iLBC with SIP
•
•
For iLBC codecs using SIP, use RFC3952 as a reference for implementation.
Mid-call codec parameter changes using SIP are supported. For example, iLBC 'mode' and 'ptime'
changes are supported using SIP during the call.
Using iLBC with H.323
•
For iLBC codecs using H.323, a new proposal is written and submitted for approval to ITU. The new
proposal is added as 'Annex S' in H245, Version 12 which is used as reference for implementation.
See H245, version 12 document at http://www.packetizer.com/ipmc/h245/
•
Mid-call codec parameter changes using H.323 are not supported.
Toll Fraud Prevention
When a Cisco router platform is installed with a voice-capable Cisco IOS software image, appropriate
features must be enabled on the platform to prevent potential toll fraud exploitation by unauthorized users.
Deploy these features on all Cisco router Unified Communications applications that process voice calls,
such as Cisco Unified Communications Manager Express (CME), Cisco Survivable Remote Site Telephony
(SRST), Cisco Unified Border Element (UBE), Cisco IOS-based router and standalone analog and digital
PBX and public-switched telephone network (PSTN) gateways, and Cisco contact-center VoiceXML
gateways. These features include, but are not limited to, the following:
•
•
•
•
•
•
•
Disable secondary dial tone on voice ports--By default, secondary dial tone is presented on voice ports
on Cisco router gateways. Use private line automatic ringdown (PLAR) for foreign exchange office
(FXO) ports and direct-inward-dial (DID) for T1/E1 ports to prevent secondary dial tone from being
presented to inbound callers.
Cisco router access control lists (ACLs)--Define ACLs to allow only explicitly valid sources of calls to
the router or gateway, and therefore to prevent unauthorized Session Initiation Protocol (SIP) or H.323
calls from unknown parties to be processed and connected by the router or gateway.
Close unused SIP and H.323 ports--If either the SIP or H.323 protocol is not used in your deployment,
close the associated protocol ports. If a Cisco voice gateway has dial peers configured to route calls
outbound to the PSTN using either time division multiplex (TDM) trunks or IP, close the unused H.
323 or SIP ports so that calls from unauthorized endpoints cannot connect calls. If the protocols are
used and the ports must remain open, use ACLs to limit access to legitimate sources.
Change SIP port 5060--If SIP is actively used, consider changing the port to something other than
well-known port 5060.
SIP registration--If SIP registration is available on SIP trunks, turn on this feature because it provides
an extra level of authentication and validation that only legitimate sources can connect calls. If it is not
available, ensure that the appropriate ACLs are in place.
SIP Digest Authentication--If the SIP Digest Authentication feature is available for either registrations
or invites, turn this feature on because it provides an extra level of authentication and validation that
only legitimate sources can connect calls.
Explicit incoming and outgoing dial peers--Use explicit dial peers to control the types and parameters
of calls allowed by the router, especially in IP-to-IP connections used on CME, SRST, and Cisco
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Overview
•
•
•
•
•
UBE. Incoming dial peers offer additional control on the sources of calls, and outgoing dial peers on
the destinations. Incoming dial peers are always used for calls. If a dial peer is not explicitly defined,
the implicit dial peer 0 is used to allow all calls.
Explicit destination patterns--Use dial peers with more granularity than .T for destination patterns to
block disallowed off-net call destinations. Use class of restriction (COR) on dial peers with specific
destination patterns to allow even more granular control of calls to different destinations on the PSTN.
Translation rules--Use translation rules to manipulate dialed digits before calls connect to the PSTN to
provide better control over who may dial PSTN destinations. Legitimate users dial an access code and
an augmented number for PSTN for certain PSTN (for example, international) locations.
Tcl and VoiceXML scripts--Attach a Tcl/VoiceXML script to dial peers to do database lookups or
additional off-router authorization checks to allow or deny call flows based on origination or
destination numbers. Tcl/VoiceXML scripts can also be used to add a prefix to inbound DID calls. If
the prefix plus DID matches internal extensions, then the call is completed. Otherwise, a prompt can
be played to the caller that an invalid number has been dialed.
Host name validation--Use the "permit hostname" feature to validate initial SIP Invites that contain a
fully qualified domain name (FQDN) host name in the Request Uniform Resource Identifier (Request
URI) against a configured list of legitimate source hostnames.
Dynamic Domain Name Service (DNS)--If you are using DNS as the "session target" on dial peers, the
actual IP address destination of call connections can vary from one call to the next. Use voice source
groups and ACLs to restrict the valid address ranges expected in DNS responses (which are used
subsequently for call setup destinations).
For more configuration guidance, see the Cisco IOS Unified Communications Toll Fraud Prevention paper.
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S.
and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.
Third-party trademarks mentioned are the property of their respective owners. The use of the word partner
does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Planning
A dial plan essentially describes the number and pattern of digits that a user dials to reach a particular
telephone number. Access codes, area codes, specialized codes, and combinations of the number of digits
dialed are all part of a dial plan. For instance, the North American public switched telephone network
(PSTN) uses a 10-digit dial plan that includes a 3-digit area code and a 7-digit telephone number. Most
PBXs support variable length dial plans that use 3 to 11 digits. Dial plans must comply with the telephone
networks to which they connect. Only totally private voice networks that are not linked to the PSTN or to
other PBXs can use any dial plan they choose.
Dial plans on Cisco routers are manually defined using dial peers. Dial peers are similar to static routes;
they define where calls originate and terminate and what path the calls take through the network.
Attributes within the dial peer configuration determine which dialed digits the router collects and forwards
to telephony devices. Dial peer configuration allows you to implement both fixed- and variable-length dial
plans for your existing voice network and enables you to adjust to future scalability needs that may arise
as your voice network expands or contracts.
This chapter contains the following sections:
•
•
•
Finding Feature Information, page 11
Fixed-Length Dial Plans, page 11
Variable-Length Dial Plans, page 12
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Fixed-Length Dial Plans
Fixed-length dialing plans, in which all the dial peer destination patterns have a fixed length, are sufficient
for most voice networks because the telephone number strings are of known lengths. Some voice networks,
however, require variable-length dial plans, particularly for international calls, which use telephone
numbers of different lengths.
If you enter the timeout T-indicator at the end of the destination pattern in an outbound voice-network dial
peer, the router accepts a fixed-length dial string and then waits for additional dialed digits. The timeout
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Planning
Variable-Length Dial Plans
character must be an uppercase T. The following dial peer configuration shows how the T-indicator is set to
allow variable-length dial strings:
dial-peer voice 1 voip
destination-pattern 2222T
session target ipv4:10.10.1.1
In the example, the router accepts the digits 2222, and then waits for an unspecified number of additional
digits. The router can collect up to 31 additional digits, as long as the interdigit timeout has not expired.
When the interdigit timeout expires, the router places the call.
The default value for the interdigit timeout is 10 seconds. Unless the default value is changed, using the Tindicator adds 10 seconds to each call setup because the call is not attempted until the timer has expired
(unless the # character is used as a terminator). You should therefore reduce the voice-port interdigit
timeout value if you use variable-length dial plans. You can change the interdigit timeout by using the
timeouts inter-digit command in voice-port configuration mode.
The calling party can immediately terminate the interdigit timeout by entering the # character. If the #
character is entered while the router is waiting for additional digits, the # character is treated as a
terminator; it is not treated as part of the dial string or sent across the network. But if the # character is
entered before the router begins waiting for additional digits (meaning that the # is entered as part of the
fixed-length destination pattern), then the # character is treated as a dialed digit.
For example, if the destination pattern is configured as 2222...T, then the entire dialed string of 2222#9999
is collected, but if the dialed string is 2222#99#99, the #99 at the end of the dialed digits is not collected
because the final # character is treated as a terminator. You can change the termination character by using
the dial-peer terminator command.
Note
In most cases, you must configure the T-indicator only when the router uses two-stage dialing. If direct
inward dialing (DID) is configured in the inbound plain old telephone system (POTS) dial peer, the router
uses one-stage dialing, which means that the full dialed string is used to match outbound dial peers. The
only exception is when the isdn overlap-receiving command is configured; the ISDN overlap-receiving
feature requires the T-indicator.
Variable-Length Dial Plans
In most voice configurations, fixed-length dialing plans, in which all the dial peer destination patterns have
the same length, are sufficient because the telephone number strings are all the same length. However, in
some voice network configurations, variable-length dial plans are required, especially if the network
connects two or more countries where telephone number strings could be different lengths.
If you enter the "T" timer character in the destination pattern for your dial peer, the router can be
configured to accept a fixed-length dial string, and then wait for additional dialed digits. For example, the
following dial peer configuration shows how the T character can be set to allow variable-length dial strings:
dial peer voice 1 pots
destination-pattern 2222T
port 1/1
In this example, the router accepts the digits 2222, and then waits for an unspecified number of dialed
digits. If digits continue to be entered before the interdigit timeout expires, then the router will continue to
gather up to 31 additional digits. Once the interdigit timeout expires, however, the router places the call.
You can configure the interdigit timeout value by using the timeouts inter-digitcommand in voice-port
configuration mode.
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Dial Planning
The interdigit timeout timer can be terminated by entering the "#" character. If the # character is entered
while the router is waiting to accept additional digits, the # character is treated as an end-dial accelerator.
The # character is not treated as an actual digit in the destination pattern and is not sent as part of the dialed
string across the network.
However, if the # character is entered before the router is ready to accept additional digits (meaning before
the "T" character is entered in the destination pattern), then the # character is treated as a dialed digit. For
example, if a destination pattern is configured with the string 2222...T, then the digits 2222####1234567
can be gathered, but the digits 2222###1234#67 cannot be gathered because the final # character is treated
as a terminator.
The default value for the interdigit timeout is 10 seconds. If the duration is not changed, using the "T" timer
adds 10 seconds to each call setup time because the call is not attempted until the timer expires (unless the
# character is used as a terminator). Because of this dependency, if a variable-length dial plan is used, the
interdigit timeout should be reduced to reduce the call setup time. For more information, refer to the
"Variable-Length Matching" section on page 37 .
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S.
and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.
Third-party trademarks mentioned are the property of their respective owners. The use of the word partner
does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Planning
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
14
Dial Peer Features and Configuration
Establishing voice communication over a packet network is similar to configuring a static route: You are
establishing a specific voice connection between two defined endpoints. Call legs define the discrete
segments that lie between two points in the call connection. A voice call over the packet network
comprises four call legs, two on the originating router and two on the terminating router; a dial peer is
associated with each of these four call legs.
Note
The example configurations in this section show voice over IP (VoIP) dial peers; the same concepts also
apply to voice over Frame Relay (VoFR) and voice over ATM (VoATM) dial peers.
•
•
•
•
•
•
Finding Feature Information, page 15
Common Practices, page 15
Data Dial Peers, page 34
Inbound and Outbound Dial Peers, page 36
Additional Features, page 43
Where to Go for Dial Peer Troubleshooting Information, page 66
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support.
To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Common Practices
The following three sections cover the bare essential configuration steps necessary to support voice
transmission and reception on a typical voice gateway router in your network:
•
•
•
Voice Ports, page 16
Session Targets, page 17
Destination Patterns, page 18
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Voice Ports
Assigning Voice Ports
Voice Ports
Your dial peer configuration cannot function until you have logically assigned a voice port to one or more
dial peers. Assigning voice ports to dial peers identifies the physical hardware in the router that will be
employed to complete voice communication to and from associated voice network endpoints.
•
Assigning Voice Ports, page 16
Assigning Voice Ports
The purpose of this task is to assign a voice port to a plain old telephone system (POTS) dial peer.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number pots
4. port string
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number pots
Example:
Enters dial-peer voice configuration mode and defines a local POTS dial
peer.
•
The numberargument identifies the dial peer. Valid entries are from 1
to 2147483647.
Router(config)# dial-peer voice 864
pots
Step 4 port string
Example:
Specifies the voice port associated with the given dial peer. The port
command syntax is platform-specific. For more information about the
syntax of this command, refer to the portcommand in the Cisco IOS Voice,
Video, and Fax Command Reference.
Router(config-dialpeer)# port 1/0:0
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Session Targets
Configuring Session Targets
Note
Voice port assignments are configured for POTS dial peers only.
Session Targets
The session target is the network address of the remote router to which you want to send a call once a local
voice-network dial peer is matched. It is configured in voice-network dial peers by using the session target
command. For outbound dial peers, the destination pattern is the telephone number of the remote voice
device that you want to reach. The session target represents the path to the remote router that is connected
to that voice device. The figure below illustrates the relationship between the destination pattern and the
session target, as shown from the perspective of the originating router.
Figure 7
Relationship Between Destination Pattern and Session Target
The address format of the session target depends on the type of voice-network dial peer:
•
•
•
•
Note
VoIP--IP address, host name of the Domain Name System (DNS) server that resolves the IP address,
ras for registration, admission, and status (RAS) if an H.323 gatekeeper resolves the IP address, or
settlement if the settlement server resolves the IP address
VoFR--Interface type and number and the data link connection identifier (DLCI)
VoATM--Interface number, and ATM virtual circuit
MMoIP--E-mail address
For inbound dial peers, the session target is ignored.
•
Configuring Session Targets, page 17
Configuring Session Targets
The purpose of this task is to assign a session target to a voice-network dial peer.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Destination Patterns
Configuring Session Targets
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number voip | vofr | voatm
4. session-target ip-address
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number voip | vofr | voatm
Enters dial-peer voice configuration mode and defines a local dial
peer.
•
Example:
The numberargument identifies the dial peer. Valid entries
are from 1 to 2147483647.
Router(config)# dial-peer voice 864 voip
Step 4 session-target ip-address
Defines the IP address identifying the next-hop location of the
voice network component associated with this dial peer.
Example:
Router(config-dialpeer)# session-target
10.45.44.43
Destination Patterns
The destination pattern associates a dialed string with a specific telephony device. It is configured in a dial
peer by using the destination-pattern command. If the dialed string matches the destination pattern, the
call is routed according to the voice port in POTS dial peers, or the session target in voice-network dial
peers. For outbound voice-network dial peers, the destination pattern may also determine the dialed digits
that the router collects and then forwards to the remote telephony interface, such as a PBX, a telephone, or
the public switched telephone network (PSTN). You must configure a destination pattern for each POTS
and voice-network dial peer that you define on the router.
•
•
Configuring Destination Patterns, page 19
Digit Manipulation, page 20
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Dial Peer Features and Configuration
Configuring Destination Patterns
Configuring Destination Patterns
The purpose of this task is to configure a destination pattern for a dial peer.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number pots | voip | vofr | voatm
4. destination-pattern + ] string[T]
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number pots | voip |
vofr | voatm
Enters dial-peer voice configuration mode and defines a local dial peer.
•
The numberargument identifies the dial peer. Valid entries are from 1 to
2147483647.
Example:
Router(config)# dial-peer voice
123 voip
Step 4 destination-pattern + ] string[T]
Example:
Defines the telephone number that identifies the destination pattern associated
with this dial peer. The keywords and argument are as follows:
•
•
Router(config-dialpeer)#
destination-pattern 5551234
+ --(Optional) Character indicating an E.164 standard number.
string --A series of digits specifying the E.164 or private dial plan telephone
number. Valid entries are as follows:
◦
•
Digits 0 through 9, letters A through D, pound sign (#), and asterisk (*),
which represent specific digits that can be entered.
◦ Comma (,), which inserts a pause between digits.
◦ Period (.), which matches any entered digit.
T --(Optional) Control character indicating that the answer-addressvalue is
a variable-length dial string.
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Dial Peer Features and Configuration
Digit Manipulation
Digit Manipulation
The router may need to manipulate digits in a dial string before it passes the dial string to the telephony
device. Which can be necessary, for instance, when calling PBXs with different capabilities to accept
digits, or for PSTN and international calls. You may need to consider different strategies for configuring
digit manipulation within your dial peers depending on your existing dial plan, the digits users are expected
to dial, and the capabilities of your PBX or key system unit (KSU). These digit-manipulation options, in
conjunction with the destination pattern, determine the dial string that the router forwards to the telephony
device.
•
•
•
•
•
•
•
•
•
Wildcards, page 20
Digit Stripping and Prefixes, page 22
Forwarding Digits, page 25
Number Expansion, page 26
Translation Rules, page 28
CreatingDigitTranslationRules, page 29
Applying Translation Rules to Inbound POTS Calls, page 31
Applying Translation Rules to Inbound VoIP Calls, page 32
Applying Translation Rules to Outbound Call Legs, page 33
Wildcards
The destination pattern can be either a complete telephone number or a partial telephone number with
wildcard digits, represented by a period (.) character. Each "." represents a wildcard for an individual digit
that the originating router expects to match. For example, if the destination pattern for a dial peer is defined
as "555....", then any dialed string beginning with 555, plus at least four additional digits, matches this dial
peer.
In addition to the period (.), several other symbols can be used as wildcard characters in the destination
pattern. These symbols provide additional flexibility in implementing dial plans and decrease the need for
multiple dial peers in configuring telephone number ranges.
The table below shows the wildcard characters that are supported in the destination pattern.
Table 3
Wildcard Symbols Used in Destination Patterns
Symbol
Description
.
Indicates a single-digit placeholder. For example,
555.... matches any dialed string beginning with
555, plus at least four additional digits.
[]
Indicates a range of digits. A consecutive range is
indicated with a hyphen (-); for example, [5-7]. A
nonconsecutive range is indicated with a comma (,);
for example, [5,8]. Hyphens and commas can be
used in combination; for example, [5-7,9].
Note Only single-digit ranges are supported. For
example, [98-102] is invalid.
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Dial Peer Features and Configuration
Wildcards
Symbol
Description
()
Indicates a pattern; for example, 408(555). It is
used in conjunction with the symbol ?, %, or +.
?
Indicates that the preceding digit occurred zero or
one time. Enter ctrl-v before entering ? from your
keyboard.
%
Indicates that the preceding digit occurred zero or
more times. This functions the same as the "*" used
in regular expression.
+
Indicates that the preceding digit occurred one or
more times.
T
Indicates the interdigit timeout. The router pauses
to collect additional dialed digits.
The table below shows some examples of how these wildcard symbols are applied to the destination pattern
and the dial string that results when dial string 4085551234 is matched to an outbound POTS dial peer. The
wildcard symbols follow regular expression rules.
Table 4
Dial Peer Matching Examples Using Wildcard Symbols
Destination Pattern
Dial String Translation
String After Stripping3
408555.+
408555, followed by one or more
wildcard digits. This pattern
implies that the string must
contain at least 7 digits starting
with 408555.
1234
408555.%
408555, followed by zero or more 1234
wildcard digits. This pattern
implies that the string must
contain at least 408555.
408555+
40855, followed by 5 repeated
one or more times.
408555%
40855, followed by 5 repeated
51234
one or more times. Any explicitly
matching digit before the %
symbol is not stripped off.
408555?
40855, followed by 5. Any
explicitly matching digit before
the ? symbol is not stripped off.
1234
51234
3 These examples apply only to one-stage dialing, where direct inward dialing (DID) is enabled on the inbound POTS dial peer. If the router is using
two-stage dialing and collecting digits one at a time as dialed, then the call is routed immediately after a dial peer is matched and any subsequent
dialed digits are lost.
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Dial Peer Features and Configuration
Digit Stripping and Prefixes
Destination Pattern
Dial String Translation
String After Stripping3
40855[5-7].+
40855, followed by 5, 6, or 7,
plus any digit repeated one or
more times.
51234
40855[5-7].%
40855, followed by 5, 6, or 7,
plus any digit repeated one or
more times.
51234
40855[5-7]+1234
40855, followed by 5, 6, or 7
repeated one or more times,
followed by 1234.
51234
408(555)+1234
408, followed by 555, which may 5551234
repeat one or more times,
followed by 1234.
In addition to wildcard characters, the following characters can be used in the destination pattern:
•
•
•
Asterisk (*) and pound sign (#)--These characters on standard touch-tone dial pads can be used
anywhere in the pattern. They can be used as the leading character (for example, *650), except on the
Cisco 3600 series.
Dollar sign ($)--Disables variable-length matching. It must be used at the end of the dial string.
Circumflex symbol (^)--When used within brackets, allows you to eliminate a digit from consideration
for dial peer matching purposes. For example, a destination pattern including [^7] would not match
any string beginning with 7.
Multiple digits can also be called out within brackets to eliminate more than one initial digit from dial peer
matching. For example, a destination pattern including [^4^6^8] would not match any digit string
beginning with 4, 6, or 8.
Note
A destination pattern including [^752] would allow matching only for digit strings beginning with 5 or 2,
but would not match any digit strings beginning with 7. This destination pattern entry essentially behaves
the same way as if you had simply included [52] in the destination pattern.
To eliminate a multiple digit string from dial peer matching consideration, you must represent each digit in
the string as a succession of individual exceptions. For example, if you wanted to eliminate matching any
digit string beginning with 537 from consideration for dial peer matching, you must ensure that your
destination pattern includes [^5][^3][^7].
The same destination pattern can be shared across multiple dial peers to form hunt groups.
Digit Stripping and Prefixes
When a terminating router receives a voice call, it selects an outbound POTS dial peer by comparing the
called number (the full E.164 telephone number) in the call information with the number configured as the
destination pattern in the POTS dial peer. The access server or router then strips off the left-justified digits
that match the destination pattern. If you have configured a prefix, the prefix is added to the front of the
3 These examples apply only to one-stage dialing, where direct inward dialing (DID) is enabled on the inbound POTS dial peer. If the router is using
two-stage dialing and collecting digits one at a time as dialed, then the call is routed immediately after a dial peer is matched and any subsequent
dialed digits are lost.
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Features and Configuration
Digit Stripping and Prefixes
remaining digits, creating a dial string, which the router then dials. If all numbers in the destination pattern
are stripped out, the user receives a dial tone.
For example, consider a voice call whose E.164 called number is 1(408) 555-2222. If you configure a
destination-pattern of "1408555" and a prefix of "9," the router strips off "1408555" from the E.164
telephone number, leaving the extension number of "2222." It then appends the prefix, "9," to the front of
the remaining numbers, so that the actual numbers dialed are "9, 2222." The comma in this example means
that the router will pause for 1 second between dialing the "9" and dialing the "2" to allow for a secondary
dial tone.
When the terminating router matches a dial string to an outbound POTS dial peer, by default the router
strips off the left-justified digits that explicitly match the destination pattern. Any remaining digits, called>
excess digits, are forwarded to the telephony interface, such as a PBX or the PSTN.
Some telephony interfaces require that any digits stripped from the dial string be recovered to support a
particular dial plan. You can strip these digits either by using the no digit-strip dial-peer voice
configuration command to disable the default digit-stripping behavior or by using the prefix dial-peer voice
configuration command to add digits to the beginning of the dial string before it is forwarded to the
telephony interface. These commands are supported only in POTS dial peers.
The no digit-strip command disables the automatic digit-stripping function so that matching digits are not
stripped from the dialed string before it is passed to the telephony interface. For example, in the following
dial peer configuration, the entire seven-digit dialed string is passed to the telephony interface:
dial-peer voice 100 pots
destination-pattern 555....
no digit-strip
port 1/0:1
Disabling digit stripping is useful when the telephony interface requires the full dialed string. With some
dial plans, however, the dialed digits must be manipulated according to specific rules. The prefix command
can be used to add specific digits to the beginning of the dialed string before it is forwarded to the
telephony interface.
For example, consider a telephone whose E.164 called number is 1(408)555-1234. This telephone can be
reached within the company by dialing its extension number, 51234. If you configure a destination pattern
of "1408555...." (the periods represent wildcards) for the associated outbound POTS dial peer, the
terminating gateway will strip off the digits "1408555" when it receives a call for 1(408)555-1234. For the
terminating gateway to forward the call to the appropriate destination, the digit "5" needs to be prepended
to the remaining digits. In this case, you would configure a prefix of 5, as shown in the following dial peer
configuration.
dial-peer voice 100 pots
destination-pattern 1408555....
prefix 5
port 1/0:1
A prefix can also include commas (,). Each comma indicates a 1-second pause in dialing. For example,
consider a telephone whose E.164 called number is 1(408)555-1234; to reach this device, you must dial
"9." In this case, you might configure "1408......." as the destination pattern, and "9" as the prefix. In this
example, the terminating router will strip the digits "1408" from the called number and append the digit "9"
to the front of the remaining digits, so that the actual number dialed is" 9,5551234." The router pauses for 1
second between dialing the "9" and the "5551234" to allow for a secondary dial tone. In this example, you
would configure the router as follows:
dial-peer voice 100 pots
destination-pattern 1408.......
prefix 9,
port 1/0:1
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Dial Peer Features and Configuration
Digit Stripping and Prefixes
Using a comma with the prefix command is useful when the router must allow for a secondary dial tone;
otherwise the router does not wait for the dial tone before playing out excess digits. Putting commas in the
prefix makes the router pause 1 second per comma, allowing for a dial tone to occur before the router
transmits the remaining digits.
The figure below shows an example of a network using the no digit-strip command. In this example, a
central site (Site D) is connected to remote sites through routers (Sites A, B, and C), and through a Centrex
system for sites still using the PSTN (Sites E and F). The Centrex service requires the full 7-digit dial string
to complete calls. The dial peers are configured with a fixed-length 7-digit dial plan.
Figure 8
Network with Digit Stripping Disabled or Prefixes Enabled
When Site E (8204...) dials 8201999, the full 7-digit dialed string is passed through the Centrex to the
router at Site D. Router D matches the destination pattern 8201... and forwards the 7-digit dial string to
Router A. Router A matches the destination pattern 8201..., strips off the matching 8201, and forwards the
remaining 3-digit dial string to the PBX. The PBX matches the correct station and completes the call to the
proper extension.
Calls in the reverse direction are handled similarly, but because the Centrex service requires the full 7-digit
dial string to complete calls, the POTS dial peer at Router D is configured with digit stripping disabled.
Alternatively, digit stripping could be enabled and the dial peer could instead be configured with a 4-digit
prefix, in this case 8204, which would result in forwarding the full dial string to the Centrex service.
Router A
Router D
dial-peer voice 1 pots
destination-pattern 8201...
port 1/0:1
!
dial-peer voice 4 vofr
destination-pattern 8204...
session target s0 2
!
dial-peer voice 5 vofr
destination-pattern 8205...
session target s0 2
!
dial-peer voice 4 pots
destination-pattern 8204...
no digit-strip
port 1/0:1
!
dial-peer voice 5 pots
destination-pattern 8205...
no digit-strip
port 1/0:1
!
dial-peer voice 1 vofr
destination-pattern 8201...
session target s0 1
!
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Dial Peer Features and Configuration
Forwarding Digits
Forwarding Digits
The forward-digits command controls the number of digits that are stripped before the dialed string is
passed to the telephony interface. On outbound POTS dial peers, the terminating router normally strips off
all digits that explicitly match the destination pattern in the terminating POTS dial peer. Only digits
matched by the wildcard pattern are forwarded. The forward-digits command can be used to forward a
fixed number of dialed digits, or all dialed digits, regardless of the number of digits that explicitly match
the destination pattern.
For example, the forward-digits 4 command tells the router to forward the last four digits in the dialed
string. The forward-digits all command instructs the router to forward the full dialed string. If the length
of the dialed string is longer than the length of the destination pattern, the forward-digits extra command
forwards the extra trailing digits. Extra digits are not forwarded, however, if the dial peer destination
pattern is variable length; for example, 123T, 123...T.
Note
The forward-digits command is supported only in POTS dial peers.
The figure below shows an example of routing voice calls through a PBX using forward digits. In this
configuration, Routers T1 and T2 are tandem nodes that must support forward digits so that calls from
Routers A, B, or C can make a call to extension 8208.
Figure 9
Routing Voice Calls Through a PBX Using Forward Digits
In this example, all digits matched with destination 8... are forwarded to the appropriate port. For a call
from Router A to reach extension 8208, the call first terminates at Router T1, which transmits the digits
8208 to the voice port connected to the PBX. The PBX then routes the voice call to Router T2. The
forward-digits all command is used here, but the forward-digits 4command could also be used in this
example.
The following dial peer configurations are required on each router for this example:
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Dial Peer Features and Configuration
Number Expansion
Router T1
Router T2
dial-peer voice 1 vofr
destination-pattern 8200
session-target s0 1
!
dial-peer voice 6 vofr
destination-pattern 8205
session-target s0 6
!
dial-peer voice 10 vofr
destination-pattern 8209
session-target s0 10
!
dial-peer voice 1 pots
destination-pattern 8...
forward-digits all
port 1/1
dial-peer voice 8 pots
destination-pattern 8208
port 1/1
!
dial-peer voice 1000 pots
destination-pattern 8...
forward-digits all
port 1/1
!
dial-peer voice 9999 pots
destination-pattern ....
forward-digits all
port 1/1
Router A
dial-peer voice 1 pots
destination-pattern 8200
port 1/1
!
dial-peer voice 1000 vofr
destination-pattern 8...
session-target s0 1
Number Expansion
In most corporate environments, the telephone network is configured so that you can reach a destination by
dialing only a portion (an extension number) of the full E.164 telephone number. You can define an
extension number as the destination pattern for a dial peer. The router can be configured to recognize the
extension number and expand it into its full E.164 dialed number when the num-exp global configuration
command is used with the destination-pattern dial-peer voice configuration command.
Number expansion is a globally applied rule that enables you to define a set of digits for the router to
prepend to the beginning of a dialed string before passing it to the remote telephony device. Automatically
prepending digits in the dial peer configuration reduces the number of digits that a user must dial to reach a
remote location. Number expansion is similar to using a prefix, except that number expansion is applied
globally to all dial peers.
Using a simple telephony-based example, suppose that user A works in a company where employees
extensions are reached by dialing the last four digits of the full E.164 telephone number. The E.164
telephone number is 555-2123; user A’s extension number is 2123. Suppose that every employee on user
A’s floor has a telephone number that begins with the same first four digits: 5552. You could define each
dial peer’s destination pattern using each extension number, and then use number expansion to prepend the
first four digits onto the extension. In this example, the router could be configured as follows:
num-exp 2... 5552...
dial peer voice 1 pots
destination pattern 2123
Number expansion can also be used to replace a dialed number with another number, as in the case of call
forwarding. Suppose that for some reason, user A needs to have all of his telephone calls forwarded to
another number, 555-6611. In this example, you would configure the router as follows:
num-exp 2123 5556611
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Dial Peer Features and Configuration
Number Expansion
dial peer voice 1 pots
destination pattern 2123
In this example, every time the device receives a call for extension 2123, the dialed digits will be replaced
with 555-6611 and the call will be forwarded to that telephone.
Before you configure the num-exp command, it is helpful to map individual telephone extensions to their
full E.164 dialed numbers. This task can be done easily by creating a number expansion table.
Creating a Number Expansion Table
The figure below shows a network for a small company that wants to use VoIP to integrate its telephony
network with its existing IP network. The destination patterns (or expanded telephone numbers) associated
with Router A are 408 115-xxxx, 408 116-xxxx, and 408 117-xxxx, where xxxx identifies the individual
dial peers by extension. The destination pattern (or expanded telephone number) associated with Router B
is 729 555-xxxx.
Figure 10
VoIP Example for Number Expansion
The table below shows the number expansion table for this scenario. The information included in this
example must be configured on both Router A and Router B.
Table 5
Sample Number Expansion Table
Extension
Destination Pattern
Num-Exp Command Entry
5....
408115....
num-exp 5.... 408115....
6....
408116....
num-exp 6.... 408116....
7....
408117....
num-exp 7.... 408117....
1...
729555....
num-exp 1... 729555....
The period (.) character represents wildcards (such as extension numbers) in a telephone number.
Configuring Number Expansion
The purpose of this task is to expand an extension number into its full telephone number.
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Dial Peer Features and Configuration
Translation Rules
SUMMARY STEPS
1. enable
2. configure terminal
3. num-exp extension-number expanded-number
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 num-exp extension-number expandednumber
Configures number expansion globally for all dial peers. The arguments
are as follows:
•
Example:
Router(config)# num-exp 2123 5556611
•
extension-number --Specifies the extension number to expand into
the full telephone number that is specified by the expanded-number
argument.
expanded-number --Specifies the full telephone number or
destination pattern to which the extension number is expanded.
Translation Rules
Digit translation rules are used to manipulate the calling number (ANI) or called number (DNIS) digits for
a voice call, or to change the numbering type of a call. Translation rules are used to convert a telephone
number into a different number before the call is matched to an inbound dial peer or before the call is
forwarded by the outbound dial peer. For example, within your company you may dial a 5-digit extension
to reach an employee at another site. If the call is routed through the PSTN to reach the other site, the
originating gateway must use translation rules to convert the 5-digit extension into the 10-digit format that
is recognized by the central office switch.
Translation rules are defined by using the translation-rule command. After you define a set of translation
rules, you can apply the rules to all inbound VoIP calls, to all inbound calls that terminate at a specific
voice port, and to individual inbound or outbound call legs according to the dial peer.
The following example shows a dial peer that is configured to use translation-rule set 1, which contains ten
translation rules. The first rule defined is rule 0, in which 910 is the pattern that must be matched and
replaced, and 0 is the pattern that is substituted for 910.
translation-rule 1
rule 0 ^910 0
rule 1 ^911 1
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Dial Peer Features and Configuration
CreatingDigitTranslationRules
rule
rule
rule
rule
rule
rule
rule
rule
2
3
4
5
6
7
8
9
^912
^913
^914
^915
^916
^917
^918
^919
2
3
4
5
6
7
8
9
!
!
dial-peer voice 2 voip
destination-pattern 91..........
translate-outgoing called 1
session target ras
The configuration results in the stripping of the leading digits 91 from any called number that begins with
91 before the number is forwarded by the outbound VoIP dial peer. Use the caret (^) symbol to specify that
the matched digits must occur at the start of a dial string.
Note
Wildcard symbols such as the period (.), asterisk (*), percent sign (%), plus sign (+), and question mark (?)
are not valid in translation rules. The router ignores these symbols when converting a number if they are
used in a translation rule.
Translation rules can also be used to change the numbering type for a call. For example, some gateways
may tag any number with more than 11 digits as an international number, even when the user must dial a 9
to reach an outside line. The following example shows a translation rule that converts any called number
that starts with 91, and that is tagged as an international number, into a national number without the 9
before sending it to the PSTN:
translation-rule 20
rule 1 91 1 international national
!
!
dial-peer voice 10 pots
destination-pattern 91..........
translate-outgoing called 20
port 1:D
!
Note
Using digit translation rules with the num-exp or prefix command is not recommended unless it is the only
way to minimize confusion.
To create digit translation rules, perform the tasks in the following sections:
•
CreatingDigitTranslationRules, page 29 (required)
To apply digit translation rules to VoIP calls, perform one or more of the following procedures:
•
•
•
Applying Translation Rules to Inbound POTS Calls, page 31 (optional)
Applying Translation Rules to Inbound VoIP Calls, page 32 (optional)
Applying Translation Rules to Outbound Call Legs, page 33 (optional)
CreatingDigitTranslationRules
The purpose of this task is to enter translation-rule configuration mode and specify a set of translation rules.
To create additional individual translation rules to include in the translation-rule set, repeat Step 4 .
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Dial Peer Features and Configuration
CreatingDigitTranslationRules
Note
Applying translation rules to more than one call leg in an end-to-end call is not recommended.
SUMMARY STEPS
1. enable
2. configure terminal
3. translation-rule name-tag
4. rule name-tag input-matched-pattern substituted-pattern [match-type substituted-type]
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 translation-rule name-tag
Example:
Router(config)# translationrule 1
Defines a digit translation-rule set and enters translation-rule configuration mode.
All subsequent commands that you enter in this mode before you exit will apply to
this translation-rule set.
•
The name-tagargument specifiesa unique number that identifies the set of
translation rules. Valid entries are from 1 to 2147483647.
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Dial Peer Features and Configuration
Applying Translation Rules to Inbound POTS Calls
Command or Action
Purpose
Step 4 rule name-tag input-matched-pattern Defines an individual translation rule. This command can be entered up to 11
times to add an individual translation rule to the translation rule set defined in Step
substituted-pattern [match-type
1. The arguments are as follows:
substituted-type]
•
Example:
•
Router(config-translate)
#
rule 0 ^910 0
•
•
•
name-tag --Specifies a unique number that identifies this individual
translation rule. Valid entries are from 0 to 10.
input-matched-pattern --Specifies the digit string that must be matched, and
then replaced with the substituted-pattern value.
substituted-pattern --Specifies the digit string that replaces the inputmatched-pattern value.
match-type --(Optional) Specifies the numbering type that you want to
replace with the numbering type defined in the substituted-type value. Enter
any for the match-type if you want to match on any numbering type.
Otherwise, enter one of the following keywords for each of these arguments:
◦
◦
◦
◦
◦
◦
◦
abbreviated
international
national
network
reserved
subscriber
unknown
Applying Translation Rules to Inbound POTS Calls
The purpose of this task is to apply a translation rule set to all inbound POTS calls that terminate on the
same voice port.
Note
When this method is used, the digit translation rules are executed before the inbound POTS dial peer is
matched.
SUMMARY STEPS
1. enable
2. configure terminal
3. voice-port location
4. translate {called | calling} name-tag
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Dial Peer Features and Configuration
Applying Translation Rules to Inbound VoIP Calls
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 voice-port location
Specifies the voice port through which the call enters the router.
The voice-port command syntax is platform-specific. For more information
about the syntax of this command, refer to the Voice Port Configuration
Guide .
Example:
Router(config)# voice-port 1/0:1
Step 4 translate {called | calling} name-tag
Example:
Router(config-voiceport)#
translate called 4
Specifies the translation rule set to apply to the called number or calling
number. The keywords and argument are as follows:
•
•
•
called --Applies the translation rule to the called party number.
calling --Applies the translation rule to the calling party number.
name-tag --Specifies the reference number of the translation rule. Valid
entries are 1 through 2147483647.
Applying Translation Rules to Inbound VoIP Calls
The purpose of this task is to apply a translation rule set to all inbound VoIP calls that originate at an H.323
gateway.
Note
When using this method, the digit translation rules are executed before the inbound VoIP dial peer is
matched.
SUMMARY STEPS
1. enable
2. configure terminal
3. voip-incoming translation-rule {called | calling} name-tag
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Dial Peer Features and Configuration
Applying Translation Rules to Outbound Call Legs
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 voip-incoming translation-rule {called | Specifies the translation rule set to apply to all inbound VoIP call legs that
originate from an H.323 gateway. The keywords and argument are as follows:
calling} name-tag
•
•
•
Example:
Router
(config)
# voip-incoming translation-rule
called 5
called --Applies the translation rule to the called party number.
calling --Applies the translation rule to the calling party number.
name-tag --Specifies the reference number of the translation rule. Valid
entries are 1 through 2147483647.
Applying Translation Rules to Outbound Call Legs
The purpose of this task is to apply a translation rule set to an outbound VoIP or POTS call leg.
Note
Translation rules that are configured in a dial peer using the translate-outgoing command are not applied
to inbound call legs. When two-stage dialing is used, the translation rules that are configured in the voice
port using the translate command are applied twice: after the inbound dial peer is matched, and again after
the digits are collected.
Note
If the prefixcommand is also configured in the dial peer, the translate-outgoing command is executed
first.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number pots | voip | vofr| voatm
4. translate-outgoing {called | calling} name-tag
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Dial Peer Features and Configuration
Data Dial Peers
DETAILED STEPS
Command or Action
Purpose
Step 1 enable
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number pots | voip | vofr|
voatm
Enters dial-peer voice configuration mode and defines a local dial peer.
•
The numberargument identifies the dial peer. Valid entries are from
1 to 2147483647.
Example:
Router(config)# dial-peer voice 345
pots
Step 4 translate-outgoing {called | calling} nametag
Specifies the translation rule set to apply to the calling number or called
number. The keywords and argument are as follows:
•
•
•
Example:
Router(config-dialpeer)# translateoutgoing called 6
called --Applies the translation rule to the called party number.
calling --Applies the translation rule to the calling party number.
name-tag --Specifies the reference number of the translation rule.
Valid entries are 1 through 2147483647.
Data Dial Peers
In addition to standard voice-network and POTS dial peers, a newer type of dial peer has been introduced
to service modem calls over POTS lines with automatic dial peer matching and priority assignment. These
new dial peers are called data dial peers.
Traditionally, if a modem call came over a POTS line connected to a voice-network gateway, a procession
of matching criteria was required to determine the nature of the incoming call. Only after it was determined
that an incoming call was not a voice call could it then be assumed that the transmission was, in fact, a
data-based modem call.
Now, however, you have the ability to specify particular daily peers as data dial peers and even assign them
priority in relation to other dial peers in the system.
•
•
Configuring Data Dial Peers, page 35
Configuring a Search for Dial Peers by Type, page 35
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Configuring Data Dial Peers
Data Dial Peers
Configuring Data Dial Peers
The purpose of this task is to configure a POTS dial peer to be a data dial peer.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer data tag pots
4. incoming called-number string
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer data tag pots
Specifies a dial peer for data calls and enters dial-peer voice configuration
mode. The keyword and argument are as follows:
•
Example:
Router(config)# dial-peer data 2001
pots
tag --Specifies the dial peer identifier. The valid range is from 1 to
2147483647.
Note You cannot have a data dial peer and a voice dial peer that are
assigned to the same tag number. The tag must be unique for all dial
peers.
•
Step 4 incoming called-number string
Specifies the incoming called number that is associated with the data dial
peer.
•
Example:
pots --Specifies the dial peer as POTS.
The stringargument specifies the number.
Router(dial-peer)# incoming callednumber 4085551212
Configuring a Search for Dial Peers by Type
The purpose of this task is to configure a search for dial peers by type.
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Dial Peer Features and Configuration
Inbound and Outbound Dial Peers
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer search type {data voice | voice data | none}
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer search type {data voice | voice data |
none}
Specifies the dial-peer search functionality. The keywords are as
follows:
•
•
•
Example:
Router(config)# dial-peer search type data
voice
data --Searches for data dial peers.
voice --Searches for voice dial peers.
none --Searches for all dial peers with the same preference
based on the input order.
Note The default is data and voice.
Inbound and Outbound Dial Peers
Dial peers are used for both inbound and outbound call legs. It is important to remember that these terms
are defined from the perspective of the router. An inbound call leg originates when an incoming call comes
to the router. An outbound call leg originates when an outgoing call is placed from the router. The first
figure below illustrates call legs from the perspective of the originating router; the second figure below
illustrates call legs from the perspective of the terminating router.
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Dial Peer Features and Configuration
Inbound and Outbound Dial Peers
Note
The figures below apply to voice calls that are being sent across the packet network. If the originating and
terminating POTS interfaces share the same router or if the call requires hairpinning, then two POTS call
legs are sufficient.
Figure 11
Call Legs from the Perspective of the Originating Router
Figure 12
Call Legs from the Perspective of the Terminating Router
For inbound calls from a POTS interface that are destined for the packet network, the router matches a
POTS dial peer for the inbound call leg and a voice-network dial peer, such as VoIP or VoFR, for the
outbound leg. For inbound calls from the packet network, the router matches a POTS dial peer to terminate
the call and a voice-network dial peer to apply features such as codec or QoS.
For inbound POTS call legs going to outbound voice-network dial peers, the router forwards all digits that
it collects. On outbound POTS call legs, the router strips off explicitly matching digits and forwards any
excess digits out the designated port.
The following examples show basic configurations for POTS and VoIP dial peers:
dial-peer voice 1 pots
destination-pattern 555....
port 1/0:1
dial-peer voice 2 voip
destination-pattern 555....
session target ipv4:192.168.1.1
The router selects a dial peer for a call leg by matching the string that is defined by using the answeraddress, destination-pattern, or incoming called-number command in the dial peer configuration.
•
•
Matching Inbound Dial Peers, page 38
Matching Outbound Dial Peers, page 42
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Matching Inbound Dial Peers
Inbound and Outbound Dial Peers
Matching Inbound Dial Peers
To match inbound call legs to dial peers, the router uses three information elements in the call setup
message and four configurable dial peer attributes. The three call setup elements are:
•
•
•
Called number or dialed number identification service (DNIS)--A set of numbers representing the
destination, which is derived from the ISDN setup message or channel associated signaling (CAS)
DNIS.
Calling number or automatic number identification (ANI)--A set of numbers representing the origin,
which is derived from the ISDN setup message or CAS ANI.
Voice port--The voice port carrying the call.
The five configurable dial peer attributes are:
•
•
•
•
•
Incoming called number--A string representing the called number or DNIS. It is configured by using
the incoming called-numberdial-peer voice configuration command in POTS or multimedia mail
over IP (MMoIP) dial peers.
Answer address--A string representing the calling number or ANI. It is configured by using the
answer-address dial-peer voice configuration command in POTS or VoIP dial peers and is used only
for inbound calls from the IP network.
Destination pattern--A string representing the calling number or ANI. It is configured by using the
destination-pattern dial-peer voice configuration command in POTS or voice-network dial peers.
Application--A string representing the predefined application that you wish to enable on the dial peer.
It is configured by using the applicationdial-peer voice configuration command on inbound POTS
dial peers.
Port--The voice port through which calls to this dial peer are placed.
The router selects an inbound dial peer by matching the information elements in the setup message with the
dial peer attributes. The router attempts to match these items in the following order:
1
2
3
4
Called number with the incoming called-number command
Calling number with the answer-address command
Calling number with the destination-pattern command
Incoming voice port with the configured voice port
The router must match only one of these conditions. It is not necessary for all the attributes to be
configured in the dial peer or that every attribute match the call setup information; only one condition must
be met for the router to select a dial peer. The router stops searching as soon as one dial peer is matched
and the call is routed according to the configured dial peer attributes. Even if there are other dial peers that
would match, only the first match is used.
Note
For a dial peer to be matched, its administrative state must be up. The dial peer administrative state is up by
default when it is configured with at least one of these commands: incoming called-number, answeraddress, or destination-pattern. If the destination-patterncommand is used, the voice port or session
target must also be configured.
•
•
•
•
Variable-Length Matching, page 39
Configuring the incoming called-number Command, page 39
answer-address Command, page 40
Configuring the destination-pattern Command, page 41
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Dial Peer Features and Configuration
Variable-Length Matching
•
Configuring the port Command, page 42
Variable-Length Matching
When matching dial peers, the router defaults to variable-length matching, which means that as long as the
left-justified digits in the dial string match the configured pattern in the dial peer, any digits beyond the
configured pattern are ignored for the purposes of matching. For example, dial string 5551212 would match
both of the following dial peers:
dial-peer voice 1 voip
destination-pattern 555
session target ipv4:10.10.1.1
dial-peer voice 2 voip
destination-pattern 5551212
session target ipv4:10.10.1.2
To disable variable-length matching for a dial peer, add the dollar sign ($) to the end of the destination
pattern, as shown:
dial-peer voice 1 voip
destination-pattern 555$
session target ipv4:10.10.1.1
The $ character in the configuration prevents this dial peer from being matched for dial string 5551212
because the extra digits beyond 555 are considered in the matching.
With two-stage dialing, the router collects the dialed string digit by digit. It attempts to match a dial peer
after each digit is received. As soon as it finds a match, it immediately routes the call. For example, given
the following configurations, the router would immediately match dial string 5551212 to dial peer 1.
dial-peer voice 1 voip
destination-pattern 555
session target ipv4:10.10.1.1
dial-peer voice 2 voip
destination-pattern 5551212
session target ipv4:10.10.1.2
If the router is performing two-stage dialing and you want to make sure that the full dial string is collected
before a dial peer is matched, you can use the timeout T-indicator as in variable-length dial plans. For
example, after the router waits until the full dial string is collected, dial string 5551212 would match both
of the following dial peers:
dial-peer voice 1 voip
destination-pattern 555T
session target ipv4:10.10.1.1
dial-peer voice 2 voip
destination-pattern 5551212T
session target ipv4:10.10.1.2
How the router selects a dial peer also depends on whether the dial peer is being matched for the inbound
or outbound call leg.
Configuring the incoming called-number Command
When a Cisco router is handling both modem and voice calls, it needs to identify the service type of the
call--that is, whether the incoming call to the router is a modem or a voice call. When the router handles
only modem calls, the service type identification is handled through modem pools. Modem pools associate
calls with modem resources based on the called number (DNIS). In a mixed environment, where the router
receives both modem and voice calls, you need to identify the service type of a call by using the incoming
called-number command.
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Dial Peer Features and Configuration
answer-address Command
If the incoming called-number command is not configured, the router attempts to resolve whether an
incoming call is a modem or voice call on the basis of the interface over which the call comes. If the call
comes in over an interface associated with a modem pool, the call is assumed to be a modem call; if a call
comes in over a voice port associated with a POTS dial peer, the call is assumed to be a voice call.
The purpose of this task is to identify the service type of a call as voice.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number pots | voip | vofr| voatm
4. incoming called-number number
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number pots | voip | vofr| voatm
Enters dial-peer voice configuration mode and defines a local
dial peer.
•
Example:
The numberargument identifies the dial peer. Valid
entries are from 1 to 2147483647.
Router(config)# dial-peer voice 345 pots
Step 4 incoming called-number number
Defines the telephone number that identifies voice calls
associated with this dial peer.
Example:
Router(config-dialpeer)# incoming called-number
5551212
answer-address Command
The purpose of this task is to specify the answer address for this dial peer.
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Dial Peer Features and Configuration
Configuring the destination-pattern Command
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number {pots | voip | vofr| voatm
4. answer-address [+] string [T]
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number {pots | voip |
vofr| voatm
Enters dial-peer voice configuration mode and defines a local dial peer.
•
The number argument identifies the dial peer. Valid entries are from 1 to
2147483647.
Example:
Router(config)# dial-peer voice
123 pots
Step 4 answer-address [+] string [T]
Defines the telephone number that identifies voice calls associated with this
dial peer. The keywords and argument are as follows:
•
•
Example:
Router(config-dialpeer)# answeraddress 55534..
+ --(Optional) Character indicating an E.164 standard number.
string --A series of digits specifying the E.164 or private dial plan
telephone number. Valid entries are as follows:
◦
•
Digits 0 through 9, letters A through D, pound sign (#), and asterisk
(*), which represent specific digits that can be entered.
◦ Comma (,), which inserts a pause between digits.
◦ Period (.), which matches any entered digit.
T --(Optional) Control character indicating that the answer-address value
is a variable-length dial string.
Configuring the destination-pattern Command
See the Configuring Destination Patterns, page 19 for information on configuring the destination pattern
for a dial peer.
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Matching Outbound Dial Peers
Configuring the port Command
Configuring the port Command
See the Assigning Voice Ports, page 16 for information on associating a voice port with a dial peer.
Matching Outbound Dial Peers
The method a router uses to select an outbound dial peer depends on whether ISDN DID is configured in
the inbound POTS dial peer. If DID is not configured in the inbound POTS dial peer, the router collects the
incoming dialed string digit by digit. As soon as one dial peer is matched, the router immediately places the
call using the configured attributes in the matching dial peer.
If DID is configured in the inbound POTS dial peer, the router uses the full incoming dial string to match
the destination pattern in the outbound dial peer. With DID, the setup message contains all the digits
necessary to route the call; no additional digit collection is required. If more than one dial peer matches the
dial string, all of the matching dial peers are used to form a rotary group. The router attempts to place the
outbound call leg using all of the dial peers in the rotary group until one is successful.
•
Using Default Routes, page 42
Using Default Routes
Default routes reduce the number of dial peers that must be configured when calls that are not terminated
by other dial peers are sent to a central router, usually for forwarding to a PBX. A default route is a dial
peer that automatically matches any call that is not terminated by other dial peers. For example, in the
following configuration, the destination pattern 8... is a voice default route because all voice calls with a
dialed string that starts with 8 followed by at least three additional digits will either match on 8208 or end
with 8..., which is the last-resort voice route used by the router if no other dial peer is matched.
dial-peer voice 8 pots
destination-pattern 8208
port 1/1
!
dial-peer voice 1000 pots
destination-pattern 8...
port 1/1
A default route could also be defined by using a single wildcard character with the timeout T-indicator in
the destination pattern, as shown in the following example:
dial-peer voice 1000 voip
destination-pattern .T
session-target ipv4:10.10.1.2
You should be careful, however, when using the T-indicator for default routes. Remember, when matching
dial peers for outbound call legs, the router places the call as soon as it finds the first matching dial peer.
The router could match on this dial peer immediately even if there were another dial peer with a more
explicit match and a more desirable route.
Note
The timeout T-indicator is appropriate only for two-stage dialing. If the router is configured for one-stage
dialing, which means that DID is configured in the inbound POTS dial peer, then the timeout T-indicator is
unnecessary.
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One Stage and Two Stage Dialing
Additional Features
Additional Features
•
•
•
•
•
•
•
•
One Stage and Two Stage Dialing, page 43
Hunt Groups, page 46
Modem Pass Through, page 50
Dual Tone Multifrequency Relay, page 53
Connection PLAR, page 55
Connection Trunk, page 57
Class of Restrictions, page 59
Configuring an iLBC Codec, page 62
One Stage and Two Stage Dialing
With two-stage dialing, when a voice call enters the network, the originating router collects dialed digits
until it can match an outbound dial peer. As soon as the router matches a dial peer, it immediately places
the call and forwards the associated dial string. No additional dialed digits are collected. The digits and
wildcards that are defined in the destination pattern determine how many digits the originating router
collects before matching the dial peer. Any digits dialed after the first dial peer is matched are dropped.
For example, if the dialed string is "1234599" and the originating router matches a dial peer with a
destination pattern of 123.., then the digits "99" are not collected. The call is placed immediately after the
digit "5" is dialed, and the dial string "12345" is forwarded to the next call leg.
On the terminating router, the left-justified digits that explicitly match the terminating POTS dial peer are
stripped off. Any trailing wildcard digits are considered excess digits. The terminating router forwards
these excess digits to the telephony interface. For example, if the dial string "1234599" is matched on a
terminating router to a destination pattern of "123..," the digits "4599" are excess digits and are forwarded
to the telephony interface.
The figure below illustrates how the originating router collects a dial string and the terminating router
forwards the digits to the telephony device.
Figure 13
Collecting and Forwarding Dialed Digits
The examples in the table below demonstrate how the originating router collects dialed digits for a given
destination pattern in the outbound voice-network dial peer.
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Dial Peer Features and Configuration
Direct Inward Dialing
Table 6
Digit Collection Based on Destination Pattern
Dialed Digits
Destination Pattern
Dial String Collected4
5551234
5......
5551234
5551234
555....
5551234
5551234
555
555
555123499
555....
5551234
•
Direct Inward Dialing, page 44
Direct Inward Dialing
Unless otherwise configured, when a voice call comes into the router, the router presents a dial tone to the
caller and collects digits until it can identify an outbound dial peer. This process is called two-stage
dialing . After the outbound dial peer is identified, the router forwards the call through to the destination as
configured in the dial peer.
The DID feature in dial peers enables the router to use the called number (DNIS) to directly match an
outbound dial peer when receiving an inbound call from a POTS interface. When DID is configured on the
inbound POTS dial peer, the called number (DNIS) is automatically used to match the destination pattern
for the outbound call leg.
Note
DID for POTS dial peers, as described here, is for ISDN connections only. It is not the same as analog DID
for Cisco routers, which supports analog DID trunk service. For more information about analog DID see
Analog Direct Inward Dialing .
You may prefer that the router use the called number (DNIS) to find a dial peer for the outbound call leg-for example, if the switch connecting the call to the router has already collected all the dialed digits. DID
enables the router to match the called number to a dial peer and then directly place the outbound call. With
DID, the router does not present a dial tone to the caller and does not collect digits; it forwards the call
directly to the configured destination. This is called one-stage dialing .
4 These examples apply only to two-stage dialing, in which the router collects the dialed string digit by digit. If DID is enabled in the inbound POTS
dial peer, the router performs one-stage dialing, which means that the full dialed string is used regardless of the destination pattern that is
matched.
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Dial Peer Features and Configuration
Configuring Direct Inward Dialing
The figure below shows a call scenario using DID.
Figure 14
VoIP Call Using DID
In the figure above, the POTS dial peer that matches the incoming called-number has DID configured:
dial-peer voice 100 pots
incoming called-number 5552020
direct-inward-dial
port 0:D
The direct-inward-dialcommand in the POTS dial peer tells the gateway to look for a destination pattern
in a dial peer that matches the DNIS. For example, if the dialed number is 5552020, the gateway matches
the following VoIP dial peer for the outbound call leg:
dial-peer voice 101 voip
destination-pattern 5552020
session target ipv4:10.1.1.2
The call is made across the IP network to 10.1.1.2, and a match is found in that terminating gateway:
dial-peer voice 555 pots
destination-pattern 5552020
port 0:D
prefix 5274200
This dial peer matches on the dialed number and changes that number to 5274200 with the prefix
command. The result is that the user dials a number, gets connected, and never knows that the number
reached is different from the number dialed.
•
Configuring Direct Inward Dialing, page 45
Configuring Direct Inward Dialing
The purpose of this task is to configure a POTS dial peer for DID.
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Hunt Groups
Configuring Direct Inward Dialing
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number pots
4. direct-inward-dial
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number pots
Enters dial-peer voice configuration mode and defines a local dial
peer that will connect to the POTS network.
•
Example:
The number argument identifies the dial peer. Valid entries are
from 1 to 2147483647.
Router(config)# dial-peer voice 234 pots
Step 4 direct-inward-dial
Specifies DID for this POTS dial peer.
Example:
Router(config-dialpeer)# direct-inward-dial
Note
DID is configured for inbound POTS dial peers only.
Hunt Groups
The router supports the concept of hunt groups, sometimes called rotary groups , in which multiple dial
peers are configured with the same destination pattern. Because the destination of each POTS dial peer is a
single voice port to a telephony interface, hunt groups help ensure that calls get through even when a
specific voice port is busy. If the router is configured to hunt, it can forward a call to another voice port
when one voice port is busy.
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Dial Peer Features and Configuration
Configuring Direct Inward Dialing
For example, in the following configuration for Router A, four POTS dial peers are configured with
different destination patterns. Because each dial peer has a different destination pattern, no backup is
available if the voice port mapped to a particular dial peer is busy with another call.
With a hunt group, if a voice port is busy, the router hunts for another voice port until it finds one that is
available. In the following example for Router B, each dial peer is configured using the same destination
pattern of 3000, forming a dial pool to that destination pattern.
Router A (Without Hunt Groups)
Router B (With Hunt Groups and Preferences)
dial-peer voice 1 pots
destination-pattern 3001
port 1/1
!
dial-peer voice 2 pots
destination-pattern 3002
port 1/2
!
dial-peer voice 3 pots
destination-pattern 3003
port 1/3
!
dial-peer voice 4 pots
destination-pattern 3004
port 1/4
dial-peer voice 1 pots
destination pattern 3000
port 1/1
preference 0
!
dial-peer voice 2 pots
destination pattern 3000
port 1/2
preference 1
!
dial-peer voice 3 pots
destination pattern 3000
port 1/3
preference 2
!
dial-peer voice 4 pots
destination pattern 3000
port 1/4
preference 3
To give specific dial peers in the pool a preference over other dial peers, you can configure the preference
order for each dial peer by using the preference command. The router attempts to place a call to the dial
peer with the highest preference. The configuration example given for Router B shows that all dial peers
have the same destination pattern, but different preference orders.
The lower the preference number, the higher the priority. The highest priority is given to the dial peer with
preference order 0. If the same preference is defined in multiple dial peers with the same destination
pattern, a dial peer is selected randomly.
By default, dial peers in a hunt group are selected according to the following criteria, in the order listed:
1 Longest match in phone number--Destination pattern that matches the greatest number of dialed digits.
For example, if one dial peer is configured with a dial string of 345.... and a second dial peer is
configured with 3456789, the router would first select 3456789 because it has the longest explicit match
of the two dial peers.
2 Explicit preference--Priority configured by using the preferencedial peer command.
3 Random selection--All destination patterns weighted equally.
You can change this default selection order or choose different methods for hunting dial peers by using the
dial-peer hunt global configuration command. An additional selection criterion is "least recent use," which
selects the destination pattern that has waited the longest since being selected.
You can mix POTS and voice-network dial peers when creating hunt groups. Mixing dial peer types can be
useful if you want incoming calls to be sent over the packet network, except that if network connectivity
fails, you want to reroute the calls back through the PBX to the PSTN. This type of configuration is
sometimes referred to as hairpinning . Hairpinning is illustrated in the figure below.
Figure 15
Voice Call Using Hairpinning
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Dial Peer Features and Configuration
Configuring Dial Peer Hunting Options
The following configuration shows an example of sending calls to the PSTN if the IP network fails:
dial-peer voice 101 voip
destination-pattern 472....
session target ipv4:192.168.100.1
preference 0
!
dial-peer voice 102 pots
destination-pattern 472....
prefix 472
port 1/0:1
preference 1
You cannot use the same preference numbers for POTS and voice-network dial peers within a hunt group.
You can set a separate preference order for each dial peer type, but the preference order does not work on
both at the same time. For example, you can configure preference order 0, 1, and 2 for POTS dial peers,
and you can configure preference order 0, 1, and 2 for the voice-network dial peers, but the two preference
orders are separate. The system resolves preference orders among POTS dial peers first.
•
•
Configuring Dial Peer Hunting Options, page 48
Configuring Dial Peer Hunting Options, page 49
Configuring Dial Peer Hunting Options
Dial peer hunting is enabled by default. The purpose of this task is to disable dial peer hunting on an
individual dial peer.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number {pots | voip | vofr | voatm
4. huntstop
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
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Dial Peer Features and Configuration
Configuring Dial Peer Hunting Options
Command or Action
Purpose
Step 3 dial-peer voice number {pots | voip | vofr | voatm Enters dial-peer voice configuration mode and defines a local dial
peer.
•
Example:
The numberargument identifies the dial peer. Valid entries are
from 1 to 2147483647.
Router(config)# dial-peer voice 345 pots
Step 4 huntstop
(Optional) Disables dial-peer hunting on the dial peer. Once you enter
this command, no further hunting is allowed if a call fails on the
selected dial peer.
Example:
Router(config-dialpeer)# huntstop
Configuring Dial Peer Hunting Options
Use the no huntstopcommand to enable dial peer hunting if it has been disabled.
The purpose of this task is to configure dial peer hunting options for all dial peers.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer hunt hunt-order-number
4. voice hunt {user-busy | invalid-number | unassigned-number}
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
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Modem Pass Through
Configuring Dial Peer Hunting Options
Command or Action
Step 3 dial-peer hunt hunt-ordernumber
Purpose
(Optional) Specifies the hunt selection order for dial peers in a hunt group. Valid
entries are 0 through 7. The default is 0. The allowable values are as follows:
•
Example:
Router(config)# dial-peer
hunt 2
•
•
•
•
•
•
•
Step 4 voice hunt {user-busy | invalidnumber | unassigned-number}
0--Specifies longest match in phone number, explicit preference, random
selection.
1--Specifies longest match in phone number, explicit preference, least recent use.
2--Specifies explicit preference, longest match in phone number, random
selection.
3--Specifies explicit preference, longest match in phone number, least recent use.
4--Specifies least recent use, longest match in phone number, explicit preference.
5--Specifies least recent use, explicit preference, longest match in phone number.
6--Specifies random selection.
7--Specifies least recent use.
(Optional) Defines how the originating or tandem router handles rotary dial peer
hunting if it receives a disconnect cause code from the terminating router. The
keywords are as follows:
Example:
•
Router(config)# voice hunt
user-busy
•
•
user-busy --Instructs the router to continue dial peer hunting if it receives a userbusy disconnect cause code from a destination router.
invalid-number --Instructs the router to stop dial peer hunting if it receives a an
invalid-number disconnect cause code from a destination router.
unassigned-number --Instructs the router to stop dial peer hunting if it receives
an unassigned-number disconnect cause code from a destination router.
Modem Pass Through
Like T.38 Fax Relay and Modem Relay, Modem Pass Through functionality can be enabled and configured
on a per-dial peer basis. Modem Pass Through behavior enables you to take advantage of features such as
the following:
•
•
•
•
Repressing bandwidth- and resource-consuming functions like compression, echo cancellation, highpass filtering, and voice activity detection (VAD).
Automatically sending redundant packets to minimize the possibility of packet loss.
Employing automatic static jitter buffers to protect against clock skew.
Identifying signals that are for modem calls versus voice or fax calls.
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Dial Peer Features and Configuration
Configuring Modem Pass Through Capability for Individual Dial Peers
The figure below illustrates a network featuring Modem Pass Through capability.
Figure 16
Modem Pass Through Connection Example
When a call over the network is identified as a modem call, both the originating and terminating voice
gateway routers automatically "roll over" to using the G.711 codec for the duration of the modem call.
Once the modem call has ceased, the digital signal processors (DSPs) in both the originating and
terminating voice gateways revert to default operation, enabling fax and voice calls to be placed and
received using those DSPs. The version of the G.711 codec you use (either a-law or u-law) is determined
by the type of network on which your voice gateways are operating and the configuration you specify using
the modem passthrough command in dial-peer voice configuration mode.
•
Configuring Modem Pass Through Capability for Individual Dial Peers, page 51
Configuring Modem Pass Through Capability for Individual Dial Peers
The purpose of this task is to configure Modem Pass Through capability for individual dial peers.
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number {pots | voip | vofr | voatm
4. modem passthrough {system | nse [payload-type number] codec {g711ulaw | g711alaw}
[redundancy]}
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
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Dial Peer Features and Configuration
Configuring Modem Pass Through Capability for Individual Dial Peers
Command or Action
Step 2 configure terminal
Purpose
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number {pots | voip |
vofr | voatm
Enters dial-peer voice configuration mode and defines a local dial peer.
•
The number argument identifies the dial peer. Valid entries are from 1 to
2147483647.
Example:
Router(config)# dial-peer voice
123 pots
Step 4 modem passthrough {system | nse
[payload-type number] codec
{g711ulaw | g711alaw}
[redundancy]}
Configures the Modem Pass Through feature for a specific dial peer. The
keywords and argument are as follows:
•
system --Defaults to the global configuration.
Note When the system keyword is used, the nse, payload-type, codec, and
redundancy keywords are not valid. Instead, the values from the global
configuration are used.
Example:
Router
(config-dialpeer)# modem
passthrough codec
g711ulaw
•
•
nse --Named signaling event.
payload-type --(Optional) NSE payload type. The number argument
specifies the value of the payload type. Valid range is from 96 to 119,
inclusive. The default value is 100.
Note When the payload type is 100, and you use the show running-config
command, the payload-type parameter does not appear in the output.
•
•
•
codec --Voice compression for speech or audio signals. Codec selections for
upspeed. The upspeed method is the method used to dynamically change the
codec type and speed to meet network conditions. This means that you might
move to a faster codec when you have both voice and data calls, and then
slow down when there is only voice traffic.
g711ulaw --Codec G.711 u-law 64000 bps for T1.
g711alaw --Codec G.711 a-law 64000 bps for E1.
Note Be sure to use the same codec type for both the originating gateway and the
terminating gateway. The g711ulaw codec is required for T1, and the
g711alaw codec is required for E1.
•
•
redundancy --(Optional) Enables packet redundancy (RFC 2198) for
modem traffic.
The default behavior for Modem Pass Through behavior in dial-peer voice
configuration mode is modem passthrough system.
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Dual Tone Multifrequency Relay
Configuring DTMF Relay and Payload Type
Dual Tone Multifrequency Relay
Dual tone multifrequency (DTMF) tones are generated when a button on a touch-tone phone is pressed.
When the tone is generated, it is compressed, transported to the other party, and then decompressed. If a
low-bandwidth codec, such as G.729 or G.723, is used without a DTMF relay method, the tone may be
distorted during compression and decompression.
DTMF relay sends DTMF tones out of band, or separately from the voice stream. Cisco gateways currently
support the following methods of DTMF relay:
•
•
•
Using a Cisco-proprietary Real-Time Transport Protocol (RTP). DTMF tones are sent in the same
RTP channel as voice data. However, the DTMF tones are encoded differently from the voice samples
and are identified by a different RTP payload type code. Use of this method accurately transports
DTMF tones, but because it is proprietary, it requires the use of Cisco gateways at both the originating
and terminating endpoints of the H.323 call.
Using either the H.245 signal or H.245 alphanumeric method. These methods separate DTMF digits
from the voice stream and send them through the H.245 signaling channel instead of through the RTP
channel. The tones are transported in H.245 User Input Indication messages. The H.245 signaling
channel is a reliable channel, so the packets that transport the DTMF tones are guaranteed to be
delivered. However, because of the overhead of using a reliable protocol, and depending on network
congestion conditions, the DTMF tones may be slightly delayed. All H.323 version 2-compliant
systems are required to support the "h245-alphanumeric" method: support of the "h245-signal" method
is optional.
Using Named Telephone Events (NTEs). Using NTE to relay DTMF tones provides a standardized
means of transporting DTMF tones in RTP packets according to section 3 of RFC 2833, RTP Payload
for DTMF Digits, Telephony Tones and Telephony Signals , developed by the IETF Audio/Video
Transport (AVT) working group. RFC 2833 defines formats of NTE RTP packets used to transport
DTMF digits, hookflash, and other telephony events between two peer endpoints. With the NTE
method, the endpoints perform per-call negotiation of the DTMF relay method. They also negotiate to
determine the payload type value for the NTE RTP packets.
Cisco H.323 gateways advertise capabilities using the H.245 capabilities messages. By default, they
advertise that they can receive all DTMF relay modes. If the capabilities of the remote gateway do not
match, the Cisco H.323 gateway sends DTMF tones as in-band voice. Configuring DTMF relay on the
Cisco H.323 gateway sets preferences for how the gateway handles DTMF transmission. If multiple
methods are configured, the priority is as follows:
•
•
•
•
Cisco RTP
RTP NTE
H.245 signal
H.245 alphanumeric
In addition to support for NTE, DTMF Relay provides support for asymmetrical payload types. Payload
types can differ between local and remote endpoints. Therefore, the Cisco gateway can transmit one
payload type value and receive a different payload type value.
•
Configuring DTMF Relay and Payload Type, page 53
Configuring DTMF Relay and Payload Type
The purpose of this task is to configure DTMF Relay capability and the respective payload type for
individual dial peers.
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Dial Peer Features and Configuration
Configuring DTMF Relay and Payload Type
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice number {voip | vofr}
4. dtmf-relay [cisco-rtp][h245-alphanumeric] [h245-signal]
5. rtp payload-type nte number
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice number {voip | vofr}
Enters dial-peer voice configuration mode and defines a remote VoIP dial peer.
The keywords and arguments are as follows:
Example:
•
Router(config)# dial-peer voice
123 voip
•
Step 4 dtmf-relay [cisco-rtp][h245alphanumeric] [h245-signal]
The numberargument is one or more digits that identify the dial peer.
Valid entries are from 1 to 2147483647.
The voip keyword indicates a VoIP peer that uses voice encapsulation on
the IP network.
Allows DTMF relay using Cisco proprietary RTP packets. DTMF tones are
encoded in the Cisco proprietary format and transported in the same RTP
channel as the voice.
Example:
Router(config-dialpeer)# dtmfrelay cisco-rtp
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Connection PLAR
Configuring Connection PLAR
Command or Action
Purpose
Step 5 rtp payload-type nte number
Identifies the payload type of an RTP packet.
•
Example:
•
Router(config-dialpeer)# rtp
payload-type nte 100
•
The nte keyword identifies the payload type as an NTE. Number values
are 96 through 127. The default value is 101.
The following numbers have preassigned values:
◦ 96
◦ 97
◦ 100
◦ 121 to 123
◦ 125 to 127
If you use these values for the NTE payload type, the command fails. You
must first reassign the value in use to a different unassigned number, for
example:
rtp payload-type nse 105
rtp payload-type nte 100
Connection PLAR
You can configure dial peers on your Cisco voice gateway router to take advantage of one-way and twoway private-line automatic ringdown (PLAR) functionality. By using the connection plar command you
can enhance your voice network to offer a number of useful features including the following:
•
•
•
Providing an off-premises extension (OPX) from a PBX, thus simulating direct connections between
FXS port users on a voice gateway router and the PBX.
Providing dial-tone from a remote PBX in order to offer toll-bypass functionality. Instead of relying on
the gateway routers in your voice network to provide dial-tone, you can employ PLAR behavior to
enable remote sites to behave as though they have a direct connection to a PBX.
Connection PLAR behavior eliminates the need for user dialing, because both of the endpoints for the
VoIP call are statically configured.
In addition to the features described, connection PLAR behavior does not dedicate bandwidth to a call
unless one or the other of the privately associated endpoints goes off-hook.
Note
The Connection PLAR and Connection Trunk feature behavior is configured on a per-voice-port basis.
Therefore, you cannot employ the same voice port for both Connection PLAR or trunk mode and collectdialed-digits mode.
•
•
Configuring Connection PLAR, page 55
Connection PLAR Design Considerations, page 57
Configuring Connection PLAR
The purpose of this task is to enable Connection PLAR on the specified dial peer.
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Dial Peer Features and Configuration
Configuring Connection PLAR
SUMMARY STEPS
1. enable
2. configure terminal
3. voice-port port-number
4. connection plar number
5. exit
6. dial-peer voice number {voip | pots}
7. port port-number
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 voice-port port-number
Enters voice-port configuration mode for the voice port
specified.
Example:
Router(config)# voice-port 1/0/0
Step 4 connection plar number
Configures the specified voice port to use the Connection PLAR
feature to automatically dial the specified digits.
Example:
Router(config-voiceport)# connection plar 51234
Step 5 exit
Returns to global configuration mode.
Example:
Router(config-voiceport)# exit
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Connection Trunk
Connection PLAR Design Considerations
Command or Action
Purpose
Step 6 dial-peer voice number {voip | pots}
Enters dial-peer voice configuration mode to configure a VoIP
or POTS dial peer.
Example:
Router(config)# dial-peer voice 123 voip
Step 7 port port-number
Configures the dial peer from the previous step to contact the
VoIP network using the specified voice port.
Example:
Router(config-dial-peer)# port 1/0/0
Connection PLAR Design Considerations
Take the following items into consideration when planning to configure Connection PLAR behavior on
your VoIP network:
•
•
•
•
Note
Because Connection PLAR is a switched VoIP call (similar to a switched virtual circuit), calls are set
up and torn down as needed--bandwidth is taken up only when a call is initiated.
Connection PLAR will operate between any types of signaling endpoints--E&M, FXO, and FXS--and
between any combination of analog and digital interfaces.
Connection PLAR does not collect digits from the connected telephony device, so you can configure
Connection PLAR without any subsequent changes to your dial plan.
Connection PLAR can be enabled on one or both of the statically configured endpoints, thus allowing
you the ability to use one-way or two-way Connection PLAR.
Because automatically forwarded digits can become distorted over the compressed VoIP audio path when
low bit rate codecs like G.729 and G.723.1 are used, you can use the dtmf relay command to transport dual
tone multifrequency (DTMF) tones out-of-band (separate from the compressed VoIP audio path) to avoid
this potential problem. For more information regarding DTMF relay configuration, refer to Dual Tone
Multifrequency Relay, page 53.
Connection Trunk
In addition to configuring Connection PLAR, you can configure your dial peers to employ the Connection
Trunk feature using the connection trunk command. Connection Trunk functionality offers some of the
same advantages as Connection PLAR, such as eliminating the need for user dialing because both of the
endpoints for the VoIP call are statically configured. In addition, Connection Trunk behavior offers you the
ability to pass supplemental call signaling capability like hookflash and point-to-point Hoot-n-Holler
between endpoints on the trunk.
However, unlike Connection PLAR, Connection Trunk endpoints are always active (or off-hook) as far as
the voice network is concerned, so bandwidth is always being allocated to a trunk that you have configured.
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Configuring Connection Trunk
Note
The Connection PLAR and Connection Trunk feature behavior is configured on a per-voice-port basis.
Therefore, you cannot employ the same voice port for both Connection PLAR or trunk mode and collectdialed-digits mode.
•
Configuring Connection Trunk, page 58
Configuring Connection Trunk
The purpose of this task is to enable Connection Trunk behavior on the specified dial peer.
SUMMARY STEPS
1. enable
2. configure terminal
3. voice-port port-number
4. connection trunk number
5. exit
6. dial-peer voice number {voip | pots}
7. port port-number
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 voice-port port-number
Enters voice-port configuration mode for the voice port
specified.
Example:
Router(config)# voice-port 1/0/0
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Configuring Connection Trunk
Command or Action
Purpose
Step 4 connection trunk number
Configures the specified voice port to use the Connection
Trunk feature to automatically dial the specified digits.
Example:
Router(config-voiceport)# connection trunk 51234
Step 5 exit
Returns to global configuration mode.
Example:
Router(config-voiceport)# exit
Step 6 dial-peer voice number {voip | pots}
Enters dial-peer configuration mode to configure a VoIP or
POTS dial peer.
Example:
Router(config)# dial-peer voice 123 voip
Step 7 port port-number
Configures the dial peer from the previous step to contact the
VoIP network using the specified voice port.
Example:
Router(config-dial-peer)# port 1/0/0
Note
Because automatically forwarded digits can become distorted over the compressed VoIP audio path when
low bit rate codecs like G.729 and G.723.1 are used, you can use the dtmf relay command to transport
DTMF tones out-of-band (separate from the compressed VoIP audio path) to avoid this potential problem.
For more information regarding DTMF relay configuration, refer to Dual Tone Multifrequency Relay,
page 53.
Class of Restrictions
The Class of Restrictions (COR) feature provides the ability to deny certain call attempts based on the
incoming and outgoing class of restrictions provisioned on the dial peers. This functionality provides
flexibility in network design, allows users to block calls (for example, to 900 numbers), and applies
different restrictions to call attempts from different originators.
COR is used to specify which incoming dial peer can use which outgoing dial peer to make a call. Each dial
peer can be provisioned with an incoming and an outgoing COR list. The incoming COR list indicates the
capability of the dial peer to initiate certain classes of calls. The outgoing COR list indicates the capability
required for an incoming dial peer to deliver a call via this outgoing dial peer. If the capabilities of the
incoming dial peer are not the same or a superset of the capabilities required by the outgoing dial peer, the
call cannot be completed using this outgoing dial peer.
A typical application of COR is to define a COR name for the number that an outgoing dial peer serves,
then define a list that contains only that COR name, and assign that list as corlist outgoing for this
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Configuring Connection Trunk
outgoing dial peer. For example, dial peer with destination pattern 5T can have a corlist outgoing that
contains COR 5x, as shown in the following configuration.
The next step, in the typical application, is to determine how many call permission groups are needed, and
define a COR list for each group. For example, group A is allowed to call 5x and 6x, and group B is
allowed to call 5x, 6x, and 1900x. Then, for each incoming dial peer, we can assign a group for it, which
defines what number an incoming dial peer can call. Assigning a group means assigning a corlist incoming
to this incoming dial peer.
dial-peer cor custom
name 5x
name 6x
name 1900x
!
dial-peer cor list listA
member 5x
member 6x
!
dial-peer cor list listB
member 5x
member 6x
member 1900x
!
dial-peer cor list list5x
member 5x
!
dial-peer cor list list6x
member 6x
!
dial-peer cor list list1900x
member 1900x
! outgoing dialpeer 100, 200, 300
dial-peer voice 100 pots
destination-pattern 5T
corlist outgoing list5x
dial-peer voice 200 pots
destination-pattern 6T
corlist outgoing list6x
dial-peer voice 300 pots
destination-pattern 1900T
corlist outgoing list1900x
!
! incoming dialpeer 400, 500
dial-peer voice 400 pots
answer-address 525....
corlist incoming listA
dial-peer voice 500 pots
answer-address 526
corlist incoming listB
Note
To configure classes of restrictions for dial peers, use the following commands beginning in global
configuration mode:
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Configuring Connection Trunk
SUMMARY STEPS
1. Router(config)# dial-peer cor custom
2. Router(config-dp-cor)# name class-name
3. Router(config-dp-cor)# exit
4. Router(config)# dial-peer cor list list-name
5. Router(config-dp-corlist)# member class-name
6. Router(config-dp-corlist)# exit
7. Router(config)# dial-peer voice number {pots | voip}
8. Router(config-dial-peer)# corlist incoming cor-list-name
9. Router(config-dial-peer)# corlist outgoing cor-list-name
DETAILED STEPS
Command or Action
Purpose
Step 1 Router(config)# dial-peer cor custom
Enters COR configuration mode to specify that named class of restrictions
apply to dial peers.
Step 2 Router(config-dp-cor)# name classname
Specifies a name for a custom class of restrictions.
Note Enter the name(dial peer cor custom) command for additional class
names, as needed. You can define a maximum of 64 COR names. These
class names are used to define the COR lists configured in Step 4 and
Step 5.
Step 3 Router(config-dp-cor)# exit
Exits COR configuration mode.
Step 4 Router(config)# dial-peer cor list listname
Defines a COR list name.
Step 5 Router(config-dp-corlist)# member
class-name
Adds a COR class to this list of restrictions.
The member is a class named in Step 2.
Note Enter the dial-peer cor listcommand and member (dial peer cor list)
command (Step 4 and Step 5) to define another list and its membership,
as needed.
Step 6 Router(config-dp-corlist)# exit
Exits COR-list configuration mode.
Step 7 Router(config)# dial-peer voice number Enters dial-peer configuration mode and defines a dial peer.
{pots | voip}
Step 8 Router(config-dial-peer)# corlist
incoming cor-list-name
Specifies the COR list to be used when this is the incoming dial peer.
Step 9 Router(config-dial-peer)# corlist
outgoing cor-list-name
Specifies the COR list to be used when this is the outgoing dial peer.
•
Note Repeat Step 7 through Step 9 for additional dial peers, as needed.
Verifying Classes of Restrictions, page 62
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Configuring an iLBC Codec
Verifying Classes of Restrictions
Verifying Classes of Restrictions
To check the validity of your classes of restrictions configuration, perform the following tasks:
•
Enter the show dial-peer voice command to learn whether the COR list fields are set as desired on a
dial peer:
Router# show dial-peer voice 210
VoiceEncapPeer210
information type = voice,
tag = 210, destination-pattern = `221',
answer-address = `', preference=0,
numbering Type = `unknown'
group = 210, Admin state is up, Operation state is up,
incoming called-number = `221', connections/maximum = 4/unlimited,
DTMF Relay = disabled,
Modem = system passthrough ,
huntstop = disabled,
application associated:
permission :both
incoming COR list:maximum capability
outgoing COR list:minimum requirement
type = pots, prefix = `221',
forward-digits default
session-target = `', voice-port = `1/0/8:D',
direct-inward-dial = enabled,
digit_strip = enabled,
•
Enter the show dial-peer corcommand to display the COR names and lists you defined:
Router# show dial-peer cor
Class of Restriction
name:900block
name:800_call
name:Catchall
COR list <list1>
member:900block
member:800_call
COR list <list2>
member:900block
COR list <list3>
member:900block
member:800_call
member:Catchall
Configuring an iLBC Codec
This section includes the following tasks:
•
•
Configuring an iLBC Codec on a Dial Peer, page 62
Configuring an iLBC Codec in the Voice Class, page 64
Configuring an iLBC Codec on a Dial Peer
The internet Low Bit-rate Codec (iLBC) is intended for packet-based communication. Perform the
following steps to configure the iLBC codec on a dial peer.
iLBC is supported on the following:
•
•
Cisco AS5350XM and Cisco AS5400XM Universal Gateways with Voice Feature Cards (VFCs)
IP-to-IP gateways with no transcoding and conferencing.
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Configuring an iLBC Codec on a Dial Peer
SUMMARY STEPS
1. enable
2. configure terminal
3. dial-peer voice tag voip
4. rtp payload-type cisco-codec-ilbc [number
5. codec ilbc [mode frame_size[bytes payload_size]]
6. exit
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enables privileged EXEC mode.
•
Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 dial-peer voice tag voip
Enters dial-peer configuration mode for the VoIP dial peer designated by tag.
Example:
Router(config)# dial-peer voice 10
voip
Step 4 rtp payload-type cisco-codec-ilbc
[number
Identifies the payload type of a Real-Time Transport Protocol (RTP) packet.
Keyword and argument are as follows:
•
Example:
Router(config-dial-peer)# rtp
payload-type cisco-codec-ilbc 100
cisco-codec-ilbc [number] --Payload type is for internet Low Bit Rate
Codec (iLBC). Range: 96 to 127. Default: 116.
Note Do not use the following numbers because they have preassigned
values: 96, 97, 100, 117, 121 to 123, and 125 to 127. If you use these
values, the command will fail. You must first reassign the value in use
to a different unassigned number, for example:
rtp payload-type nse 105
rtp payload-type cisco-codec-ilbc 100
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Troubleshooting Tips
Command or Action
Purpose
Step 5 codec ilbc [mode frame_size[bytes
payload_size]]
Specifies the voice coder rate of speech for a dial peer. Keywords and
arguments are as follows:
•
Example:
Router(config-dial-peer)# codec
ilbc mode 30 bytes 200
Step 6 exit
•
mode frame_size --The iLBC operating frame mode that will be
encapsulated in each packet. Valid entries are 20 (20ms frames for
15.2kbps bit rate) or 30 (30ms frames for 13.33 kbps bit rate). Default is
20.
bytes payload_size --Number of bytes in an RTP packet. For mode 20,
valid values are 38 (default), 76, 114, 152, 190, and 228. For mode 30,
valid values are 50(default), 100, 150, and 200.
Exits the current mode.
Example:
Router(config-dial-peer)# exit
•
•
Troubleshooting Tips, page 64
What to Do Next, page 64
Troubleshooting Tips
You can use the following commands to check iLBC status:
•
•
•
•
•
•
•
•
show voice call summary
show voice call status
show voice dsmp stream
show call active voice
show call history voice
show voice dsp and its extensions
show dial-peer voice
show voice dsp channel operational-status
What to Do Next
To set the codec preference, see the "Configuring Multiple Codecs" section in the Cisco IOS H.323
Configuration Guide .
Configuring an iLBC Codec in the Voice Class
When using multiple codecs, you must create a voice class in which you define a selection order for
codecs; then, you can apply the voice class to VoIP dial peers. The voice class codec global configuration
command allows you to define the voice class that contains the codec selection order. Then, use the voiceclass codec dial-peer configuration command to apply the class to individual dial peers.
To configure an iLBC codec in the voice class for multiple-codec selection order, perform the following
steps.
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Configuring an iLBC Codec in the Voice Class
Follow these procedures to create a voice class. For the complete dial-peer configuration procedure, see the
Common Practices, page 15.
You can configure more than one voice class codec list for your network. Configure the codec lists and
apply them to one or more dial peers based on which codecs (and the order) you want supported for the dial
peers. Define a selection order if you want more than one codec supported for a given dial peer.
SUMMARY STEPS
1. enable
2. configure terminal
3. voice class codec tag
4. codec preference value ilbc [mode frame_size] [bytes payload_size]
5. exit
6. dial-peer voice tag voip
7. voice-class codec tag
8. exit
DETAILED STEPS
Command or Action
Step 1 enable
Purpose
Enters privileged EXEC mode. Enter your password if prompted.
Example:
Router> enable
Step 2 configure terminal
Enters global configuration mode.
Example:
Router# configure terminal
Step 3 voice class codec tag
Example:
Enters voice-class configuration mode and assigns an identification tag
number for a codec voice class. The argument is as follows:
•
tag --Unique identifier on the router. Range: 1 to 10000.
Router(config)# voice class codec 99
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Where to Go for Dial Peer Troubleshooting Information
Command or Action
Step 4 codec preference value ilbc [mode
frame_size] [bytes payload_size]
Purpose
Specifies a list of preferred codecs to use on a dial peer. Keywords and
arguments are as follows:
•
Example:
•
Router(config-voice-class)# codec
preference 1 ilbc 30 200
•
Step 5 exit
value --Order of preference, with 1 being the most preferred and 14
being the least preferred.
mode frame_size --The iLBC operating frame mode that will be
encapsulated in each packet. Valid entries are 20 (20ms frames for
15.2kbps bit rate) or 30 (30ms frames for 13.33 kbps bit rate). Default is
20.
bytes payload_size --Number of bytes in an RTP packet. For mode 20,
valid values are 38 (default), 76, 114, 152, 190, and 228. For mode 30,
valid values are 50(default), 100, 150, and 200.
Exits the current mode.
Example:
Router(config-voice-class)# exit
Step 6 dial-peer voice tag voip
Enters dial-peer configuration mode for the specified VoIP dial peer.
Example:
Router(config)# dial-peer voice 16
voip
Step 7 voice-class codec tag
Assigns a previously configured codec selection preference list (the codec
voice class that you defined in step 3) to the specified VoIP dial peer.
Note The voice-class codeccommand in dial-peer configuration mode
Example:
Router(config-dial-peer)# voiceclass codec 99
Step 8 exit
contains a hyphen. The voice class command in global configuration
mode does not contain a hyphen.
Exits the current mode.
Example:
Router(config-dial-peer)# exit
Where to Go for Dial Peer Troubleshooting Information
Dial peer troubleshooting consists of a vast array of techniques applicable to a variety of dial peer
configuration practices. This document does not cover the techniques necessary to effectively troubleshoot
potential pitfalls relating to dial peer configuration. Instead, refer to the TAC Web Site at http://
www.cisco.com/public/support/tac/technologies.shtml.
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Dial Peer Features and Configuration
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S.
and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks.
Third-party trademarks mentioned are the property of their respective owners. The use of the word partner
does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology diagrams,
and other figures included in the document are shown for illustrative purposes only. Any use of actual IP
addresses or phone numbers in illustrative content is unintentional and coincidental.
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Configuring an iLBC Codec
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Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature
information and caveats, see the release notes for your platform and software release. To find information
about the features documented in this module, and to see a list of the releases in which each feature is
supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image
support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is
not required.
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Dial Peer Configuration Examples
This appendix contains a series of configuration examples featuring the minimum required components
and critical Cisco IOS command lines extracted from voice gateway configuration files necessary to
complete an endpoint-to-endpoint call. Each example is designed to focus on a specific combination of
components or configuration concept essential to voice over IP (VoIP) communication. This appendix
covers the following topics:
•
•
•
•
•
Two Analog Phones, page 71
Two Fax Machines, page 73
An Analog Phone and an IP Phone Connected over an IP Network, page 74
Two IP Phones Connected via a Voice over Frame Relay Network, page 75
Using Digit Manipulation to Overcome the Obstacle of an IP Network Failure, page 77
Two Analog Phones
The simplest and most ubiquitous implementation of dial peer configuration involves connecting two
standard analog telephones over an IP network. The following two examples illustrate the minimum
required configurations necessary to connect two analog phones, where they are attached to the same voice
gateway router and where each phone is attached to its own voice gateway router via FXS ports installed in
the voice gateway routers in question.
•
•
•
Both Connected to the Same Voice Gateway Router, page 71
Each Connected to Their Own Voice Gateway Routers Using the G.711 Codec, page 72
Each Connected to Their Own Voice Gateway Routers Using the G.729r8 Codec, page 73
Both Connected to the Same Voice Gateway Router
Figure 17
Two analog phones connected to the same voice gateway router
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Each Connected to Their Own Voice Gateway Routers Using the G.711 Codec
Two Analog Phones
Voice Gateway Router Configuration File
voice-port 1/0/0
!
voice-port 1/0/1
!
!
dial-peer voice 1 pots
destination-pattern 5551234
port 1/0/0
!
dial-peer voice 2 pots
destination-pattern 5555678
port 1/0/1
Each Connected to Their Own Voice Gateway Routers Using the G.711
Codec
Figure 18
Two analog phones each connected to their own voice gateway router
Voice Gateway Router 1 Configuration File
voice-port 1/0/0
!
dial-peer voice 1 pots
destination-pattern 5551234
port 1/0/0
!
dial-peer voice 10 voip
destination-pattern 5555678
session target ipv4:10.5.6.7
codec g711ulaw
Voice Gateway Router 2 Configuration File
voice-port 1/0/0
!
dial-peer voice 2 pots
destination-pattern 5555678
port 1/0/0
!
dial-peer voice 20 voip
destination-pattern 5551234
session target ipv4:10.2.3.4
codec g711ulaw
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Each Connected to Their Own Voice Gateway Routers Using the G.729r8 Codec
Two Fax Machines
Each Connected to Their Own Voice Gateway Routers Using the G.729r8
Codec
Voice Gateway Router 1 Configuration File
voice class codec 1
codec preference 1 g729r8
codec preference 2 g711ulaw
!
voice-port 1/0/0
!
voice-port 1/0/1
!
!
dial-peer voice 1 pots
destination-pattern 5551234
port 1/0/0
!
dial-peer voice 2 voip
destination-pattern 5555678
voice-class codec 1
session target ipv4:10.5.6.7
Voice Gateway Router 2 Configuration File
voice class codec 1
codec preference 1 g729r8
codec preference 2 g711ulaw
!
voice-port 1/0/0
!
voice-port 1/0/1
!
!
dial-peer voice 1 pots
destination-pattern 5555678
port 1/0/0
!
dial-peer voice 2 voip
destination-pattern 5551234
voice-class codec 1
session target ipv4:10.2.3.4
Two Fax Machines
Once the connection between two analog phones over the IP network can be set up, you can then alter the
configuration slightly to enable fax communication over the IP network. The figure below illustrates the
configuration files necessary to establish T.38 Fax Relay functionality over the IP network.
Figure 19
Two fax machines connected via T.38 Fax Relay
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Dial Peer Configuration Examples
An Analog Phone and an IP Phone Connected over an IP Network
Voice Gateway Router 1 Configuration File
interface FastEthernet0/0
ip address 10.21.9.4 255.255.255.0
!
voice-port 1/0/0
!
voice-port 1/0/1
!
dial-peer voice 1 pots
destination-pattern 5551234
port 1/0/0
!
dial-peer voice 2 voip
destination-pattern 5555678
session target ipv4:10.5.6.7
codec g711ulaw
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback cisco
fax rate voice
Voice Gateway Router 2 Configuration File
interface FastEthernet0/0
ip address 10.21.7.61 255.255.255.0
!
voice-port 1/0/0
!
voice-port 1/0/1
!
dial-peer voice 1 pots
destination-pattern 5555678
port 1/0/0
!
dial-peer voice 2 voip
destination-pattern 5551234
voice-class codec 1
session target ipv4:10.2.3.4
codec g711ulaw
fax protocol t38 ls-redundancy 0 hs-redundancy 0
fax rate voice
An Analog Phone and an IP Phone Connected over an IP
Network
Once you are able to establish the connection of two analog phones over an IP network, you can then
expand the scope of configuration coverage to include an analog phone and an IP phone connected over the
IP network. The configuration for each of the voice gateway routers is essentially the same as if you were
connecting two analog phones; you will need to ensure that you have allowed for a Cisco CallManager
server connection to the appropriate Cisco voice gateway router to accommodate the introduction of the IP
phone.
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Dial Peer Configuration Examples
Two IP Phones Connected via a Voice over Frame Relay Network
Note
A CallManager server has been used in this configuration to manage the Cisco IP phone. However, this
document does not address Cisco CallManager configuration. For more information on Cisco CallManager
setup and configuration, refer to the Cisco CallManager documentation available on Cisco.com.
Figure 20
An analog phone and an IP phone each connected to their own voice gateway router
Voice Gateway Router 1 Configuration File
voice-port 1/0/0
!
dial-peer voice 1 pots
destination-pattern 5551234
port 1/0/0
!
dial-peer voice 2 voip
destination-pattern 5555678
session target ipv4:10.5.6.7
Voice Gateway Router 2 Configuration File
voice-port 1/0/0
!
dial-peer voice 1 pots
destination-pattern 5555678
port 1/0/0
!
dial-peer voice 2 voip
destination-pattern 5551234
session target ipv4:10.2.3.4
Two IP Phones Connected via a Voice over Frame Relay
Network
The examples thus far in this appendix have described connecting endpoints over an IP network based
primarily on Ethernet connections. However, you may find that you must configure a Frame Relay WAN to
effectively serve the voice communications demands for your system. The figure below and the subsequent
Cisco voice gateway router configuration examples illustrate the dial peer configuration and Frame Relay
Cisco IOS commands necessary to enable Frame Relay communication across your IP network.
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Dial Peer Configuration Examples
Two IP Phones Connected via a Voice over Frame Relay Network
Note
Although it is an essential portion of the configuration of this system, and the following configuration files
contain the Cisco IOS commands necessary to establish Frame Relay connectivity, Frame Relay
configuration is not addressed in this document. For more information on Frame Relay configuration, refer
to the appropriate documentation available on Cisco.com.
Figure 21
Two IP phones connected over a Frame Relay network
Voice Gateway Router 1 Configuration File
The configuration for this voice gateway features a Cisco 3620 running Cisco IOS Release 12.2(11)T6.
interface Serial0/0
ip address 10.2.1.1 255.0.0.0
encapsulation frame-relay
!
voice-port 1/0/0
!
voice-port 1/0/1
!
voice-port 1/1/0
!
voice-port 1/1/1
!
dial-peer cor custom
!
dial-peer voice 1 pots
destination-pattern 5551234
port 1/0/0
!
dial-peer voice 1000 voip
preference 1
destination-pattern 5555678
session target ipv4:10.5.6.7
Voice Gateway Router 2 Configuration File
The configuration for this voice gateway features a Cisco 3620 running Cisco IOS Release 12.2(15)T.
interface Serial0/0
ip address 10.2.3.4 255.0.0.0
encapsulation frame-relay
clockrate 2000000
no fair-queue
!
voice-port 1/0/0
!
voice-port 1/0/1
!
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Using Digit Manipulation to Overcome the Obstacle of an IP Network Failure
voice-port 1/1/0
!
voice-port 1/1/1
!
dial-peer cor custom
!
dial-peer voice 1 pots
destination-pattern 5555678
port 1/0/0
!
dial-peer voice 2000 voip
preference 1
destination-pattern 5551234
session target ipv4:10.2.3.4
Using Digit Manipulation to Overcome the Obstacle of an IP
Network Failure
The figure below and the subsequent Cisco voice gateway router configuration examples illustrate the dial
peer configuration necessary to automatically route an outgoing voice call over the PSTN in the event of a
temporary IP network outage. An advantage to this method of setting up and connecting the call over the
PSTN (while still originating the transmission from a voice gateway router) is more commonly known as
"toll bypass."
Figure 22
Using the PSTN in the event of an IP network failure
Voice Gateway Router 1 Configuration File
The configuration for this voice gateway features a Cisco 3620 running Cisco IOS Release 12.2(15)T.
translation-rule 21
Rule 1 ^2 5552
!
translation-rule 11
Rule 1 ^5551 1
!
interface FastEthernet0/0
ip address 10.1.1.2 255.255.255.0
duplex auto
speed auto
!
voice-port 1/0/0
translate called 11
!
voice-port 1/0/1
!
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Dial Peer Configuration Examples
Using Digit Manipulation to Overcome the Obstacle of an IP Network Failure
voice-port 1/1/0
!
voice-port 1/1/1
!
dial-peer cor custom
!
dial-peer voice 1 pots
destination-pattern 1000
port 1/1/0
!
dial-peer voice 2000 voip
preference 1
destination-pattern 2000
session target ipv4:10.1.1.3
!
dial-peer voice 20 pots
preference 2
destination-pattern 2000
translate-outgoing called 21
port 1/0/0
forward-digits all
Voice Gateway Router 2 Configuration File
The configuration for this voice gateway features a Cisco 3620 running Cisco IOS Release 12.2(11)T6.
translation-rule 11
Rule 1 ^1 5551
!
translation-rule 21
Rule 1 ^5552 2
!
interface Ethernet0/0
ip address 10.1.1.3 255.255.255.0
full-duplex
!
voice-port 1/0/0
!
voice-port 1/0/1
!
voice-port 1/1/0
translate called 21
!
voice-port 1/1/1
!
dial-peer cor custom
!
dial-peer voice 1 pots
destination-pattern 2000
port 1/0/0
!
dial-peer voice 1000 voip
preference 1
destination-pattern 1000
session target ipv4:10.1.1.2
!
dial-peer voice 10 pots
preference 2
destination-pattern 1000
translate-outgoing called 11
port 1/1/0
forward-digits all
Dial Peer Configuration on Voice Gateway Routers, Cisco IOS Release 12.4T
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Third-party trademarks mentioned are the property of their respective owners. The use of the word partner
does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be
actual addresses and phone numbers. Any examples, command display output, network topology
diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of
actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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