User Guide

MTC Data/FAX Advanced Data Addendum
AT Command Set December 4, 1996
2 Lucent Technologies Inc.
AT Commands Reference
AT commands are issued to the modem to control the modem's operation and software configuration. AT
commands can only be entered while the modem is in command mode. The format for entering AT commands is:
TYPE: ATXn
where X is the AT command, and n is the specific value for that command.
PRESS: Enter
Any command issued is acknowledged with a response in either text or numeric values known as result codes.
Table 2 lists all the valid result codes.
In the following listing, all commands and command-values accepted by the modem are shown; any entries other
than those shown cause the ERROR result code.
+++ Escape sequence
The escape sequence allows the modem to exit data mode and enter on-line command mode. While in on-line
command mode, you may communicate directly to your modem using AT commands. Once you are finished, you
may return to data mode using the ATO command.
A pause, the length which is set by the Escape Guard Time (S12), must be used after an escape sequence is
issued. This pause prevents the modem from interpreting the escape sequence as data.
The value of the escape sequence character may be changed using Register S2.
A/ Repeat Last Command
This command repeats the last command string entered. Do not precede this command with an AT prefix or
conclude it by pressing Enter.
A Answer Command
This command instructs the modem to go off-hook and answer an incoming call.
Bn Communication Standard Setting
This command determines CCITT vs. Bell standard.
B0: Selects CCITT V.22 mode when the modem is at 1200 bits/s.
B1: Selects Bell 212A when the modem is at 1200 bits/s (default).
B2: Unselects V23 reverse channel ( same as B3 ).
B3: Unselects V23 reverse channel ( same as B2 ).
B15: Selects V.21 when the modem is at 300 bits/s.
B16: Selects Bell 103J when the modem is at 300 bits/s (default).
Result Codes:
OK n = 0, 1, 15, 16
ERROR Otherwise