PBX Networking Connections
12.1
Connections
Networking two or more TK systems means interconnecting them. The
OpenCom 100 allows you to use the following connections:
■ ISDN trunk lines
■ ISDN point-to-point connections (Q.SIG) on external S
0
ports or on the S
2M
port
■ IP network connections (Q.SIG-IP)
PBX PBX PBX PBX
PBX
Trunk line
Point-to-point connection
Example of a PBX network
Various line types and transmission protocols can be used for point-to-point connections. The required network topology (distance, connection capacity) determines which type of point-to-point connection is most suitable.
12.1.1 Protocol: Q.SIG or DSS1
The Q.SIG protocol, designed for ISDN point-to-point connections, is the preferable choice as the transmission protocol; alternatively, the DSS1 protocol, designed for ISDN dial-up connections in the Euro-ISDN, can be used. Certain PBX networking features can only be used with the Q.SIG/Q.SIG-IP protocol, however.
In particular, the identifier indicating whether a call is internal or external cannot be transmitted using DSS1.
Both protocols implement communication on several protocol layers:
■ L1: Layer 1 defines the physical line properties and the electrical coding of signals.
■ L2: Layer 2 enables communication via individual error-protected channels that are independent of each other.
■ L3: Layer 3 defines the administration of the individual channels and implements the features designed for ISDN.
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