Dial Modifier Commands. Multitech MT1432BA, MT2834BAI, MT2834BA

MultiModemBA User Guide

To activate DTR Dialing, enter AT$D1 and hit RETURN. The modem dials the phone number stored in the N0 location of memory when it receives a high DTR signal. DTR must remain high for the duration of the call, until disconnect. To deactivate DTR dialing, enter AT$D0 and hit RETURN.

Note when using DTR Dialing in a synchronous application, be sure DIP-Switch #8 is in the UP position to disable V.25bis Command mode.

Voice/Data Dialing $VD

Another alternate method of causing the modem to automatically dial is Voice/Data Dialing. With

Voice/Data Dialing, the modem automatically dials the phone number stored in the N1 position of memory whenever the Voice/Data switch is toggled. You must first enter AT$VD1&W0<CR>. This command string enables Voice/Data dialing when the Voice/Data toggle switch is activated. To disable Voice/Data Dialing (default), enter the command AT$VD0 W0<CR>.

5.4.2

Dial Modifier Commands

There are several command characters that can be included within a dialing command (following the letter D), called “Dial Modifiers”. They have various functions, including the selection of Pulse or Tone

Dialing, pauses in the dial sequence, automatic re-dials if a number is busy, and reverting to the

Command mode or switching to the Answer mode after dialing.

Pulse or Tone Dial P T

The modem dials numbers using either pulse or tone dialing, or a combination of both methods.

Pulse dialing is a method used by rotary-dial telephones, which involves the timed opening and closing of line relay.

Tone dialing is the method used by push-button (touch tone) telephones, and is sometimes referred to as DTMF, or Dual-Tone Multi-Frequency dialing.

The method used is selected by including a P for Pulse or a T for Tone in the dialing command, right before the digits you wish to have dialed in that manner.

For example, you would pulse-dial the number 555-1212 by entering ATDP5551212 and hitting

RETURN. You could tone-dial the same number by entering ATDT5551212 and hitting RETURN. If neither Pulse nor Tone dialing is specified in the dial command, the modem uses whatever method used last. If the modem has been reset or just powered up, it uses Pulse dialing, even if the letter P is not included in your dial command.

Nearly all telephone systems in the U.S. are now compatible with tone dialing. Since that is the faster method, you will probably choose the tone method for your dialing.

An example of combining pulse and tone dialing could involve a PBX system where 9 had to be pulse-dialed first, then the rest of the number tone-dialed after pausing for a second dial tone. The number would be dialed by entering ATDP9, T5551212 and RETURN. (The comma causes a pause, which we’ll explain soon.)

Set Pulse Dial Ratios &P

This command sets the time ratios between the open and closed portions of the dialing pulse frequencies. To set the dialing pulse ratio of 60 mSec to 40 mSec, enter AT&P0. To set a ratio of 67 mSec to 33 mSec, enter AT&P1. The factory default is &P0.

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Chapter 5 - Command Mode

Automatic Pauses in Dialing ,

You can cause the modem to pause during the dialing sequence by entering a comma character where the pause is desired. This pause lasts two seconds. If a longer pause is desired, more than one comma may be entered consecutively, with each comma causing a two second pause. You also have the option of changing the length of the pause caused by the comma, from two seconds to any other value from 0 up to 255 seconds. This is done by setting S-Register S8 (refer to

Chapter 6

).

Each comma in a dialing command counts as one of the sixty allowed characters.

Long Space Disconnect Y

When two modems are connected in Normal mode (i.e. without error correction) there is no "polite" means of requesting a disconnect. A link disconnect request packet is sent under reliable connections. As a result some "garbage" may be received when a hang-up command is issued. The

Y1 command enables the modem to use the break signal which accomplishes the hang-up as an instruction to shut off its receiver and disconnect (both modems must have Y1 enabled for this feature to be effective). Y0 (factory default) disables this function.

Wait for New Dial-Tone W

A W inserted in the dialing command causes the modem to wait for another dial tone, and not resume dialing until another dial tone is detected.

It is not necessary to enter a W at the beginning of the dialing command to wait for a modem dial tone, because the modem will do that first (pause automatically).

In order for this command to work, you must select Wait-For-Dial Tone dialing with the X2 or X4 command, so that your modem will be able to detect the dial tone.

Return to Command Mode After Dial Command Execution ;

A semicolon (;), entered as the last character of a dialing command causes the modem to return to the Command mode immediately after executing the command, instead of waiting for a carrier signal and going on line.

For example, entering ATDT5551212; would tone-dial the number, and do nothing afterwards except go back into Command mode. This can be useful in dialing applications where modem data transfer is not desired, such as voice communications, or in applications involving the use of touch tones as a data entry method, such as bank-by-phone.

Reverse the Mode of Operation R

In certain operations you may need to reverse the mode of operation for your modem from originate to answer or answer to originate so that it would answer the phone and go into answer mode. This command turns off the reversing function with the R0 command and turns it on with the R1 command with the modem in either command mode. If you want to reverse from the originate mode, use R (with no number) in the dialing string.

Flash On Hook !

Some switchboard systems react to a momentary On Hook. An exclamation mark inserted in the command causes the modem to “flash” on hook for a half of a second, as if you had held the switch hook button on a telephone down for a half second.

For example, to flash On Hook after dialing the number 555-1234 in order to transfer to Extension

#5678, you might enter ATDT5551234,,!5678. The commas cause a 4 second pause (just to be safe).

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MultiModemBA User Guide

"Calling Card" Detect Tones $

The modem has the capability to detect AT&T "calling card" tones for the purpose of utilizing the user's calling card number to originate an on-line connection. An $ symbol placed in the dialing string causes the modem to pause and wait for an AT&T "calling card" or a 1600 Hz tone (prevalent in the

United Kingdom). When the tone is detected, the rest of the dialing string is processed. If no tones are detected within the time period set by S-Register S7 (default 45 seconds), the modem will abort by indicating a NO CARRIER message. Hitting any key also aborts the $ command.

The following is an example of this command:

ATDT

1028806127853500

$

123456789

(access/phone number) (credit card number)

Quiet Answer @

The @ command causes the modem to wait before processing the next symbol in the dialing string.

The wait is for one or more ringbacks followed by 5 seconds of silence. If the time specified by S-

Register S7 passes before the rings and silence, a NO ANSWER (R) result code is processed. The

@ command is used for accessing a system that does not provide a dial tone.

For example, ATDT5551212@6313550 causes the modem to dial the first number (555-1212) and wait for the time specified in S7 for at least one ringback and 5 seconds of silence. If a busy signal is detected, the modem hangs up and generates a BUSY result code. If it does not detect 5 seconds of silence, a NO ANSWER result code is generated after hanging up. If 5 seconds of silence is detected, the second number (631-3550) is then dialed.

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