3-2
3.2.
AT COMMAND SET
The modem will respond to the commands detailed below. Parameters applicable to each command are listed with the command description.
The defaults shown for each configuration command are those used in the factory profile.
3.2.1. AT Commands
A/ - Re-execute Command
The modem behaves as though the last command line had been re-sent by the DTE.
“
A/
”
will repeat all the commands in the command
buffer.The principal application of this command is to place another call (using the Dial command) that failed to connect due to a busy line, no
answer, or a wrong number. This command must appear alone on a command line. This command should not be terminated by a carriage
return.
AT= x - Write to Selected S-Register
This command writes the value x to the currently selected S-Register. An S-Register can be selected by using the ATSn command. All of the
S-Registers will return the OK response if x is a number.
Result Codes:
OK
For all arguments.
AT? - Read Selected S-Register
This command reads and displays the selected S-Register. An S-Register can be selected by using the ATSn command.
Result Codes:
OK
For all arguments.
A - Answer
The modem will go off-hook and attempt to answer an incoming call if correct conditions are met. Upon successful completion of answer
handshake, the modem will go on-line in answer mode. If +FCLASS=0 is selected, the modem will enter the connect state after exchanging
carrier with the remote modem. If no carrier is detected within a period specified in register S7, the modem hangs up. Any character entered
during the connect sequence will abort the connection attempt.If +FCLASS=1 or 2 is selected to prepare the modem to answer a Fax call, the
modem will go off-hook in V.21 answer mode. It will generate the V.21 2100 Hz answer tone for 3
±
0.5 seconds and, following a delay of 70
ms, will proceed as if the +FTH=3 command were issued. At any stage up to (but excluding) the +FTH=3 command state, any character will
abort the communication. (See the description of the +FTH command for details.)
Bn - CCITT or Bell
When the modem is configured to allow either option, the modem will select Bell or CCITT modulation for a line speed connection of 300 or
1200 bps according to the parameter supplied. Any other line speed will use a CCITT modulation standard. The parameter value, if valid, is
written to S27 bit 6. (Also, see ATFn command.
B0
Selects CCITT operation at 300 or 1200 bps during Call Establishment and a subsequent connection.
B1
Selects BELL operation at 300 or 1200 bps during Call Establishment and a subsequent connection. (Default)
Result Codes:
OK
n = 0 or 1.
ERROR
Otherwise.
Cn - Carrier Control
This command is included for compatibility only, and has no effect other than returning a result code. The only valid parameter is 1.Result
Codes:
OK
n = 1.
ERROR
Otherwise.
