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Appendix A: AT Command Set
AT Commands
AT commands are issued to the modem to control the modem’s operation and soft-
ware configuration. AT commands can only be entered while the modem is in com-
mand mode. Enter AT commands by typing:
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. To issue multiple AT commands on the same command
line, the commands are executed in the order they are received. Should execution of
a command result in an error, or a character not be recognized as a valid command,
execution is terminated, the remainder of the command line is ignored, and the
ERROR result code is issued. Otherwise, if all commands execute correctly, only the
result code associated with the last command shall be issued; result codes for preced-
ing commands are suppressed.
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 com-
mand 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 of which is set by the Escape
Guard Time S-Register (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 com-
mand 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.
