At Command Descriptions - Compaq 244100-005 - Deskpro 2000 - 16 MB RAM White Paper

Compaq V.90 Integrated Modem Commands

AT Command Descriptions

+++ Escape sequence
The escape sequence allows the modem to exit data mode and enter online command mode.
While in online 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:
B1:
B2:
B3:
B15:
B16:
Result Codes:
OK
ERROR
Cn Carrier Control
The modem will accept the C1 command without error in order to assure backward compatibility
with communications software that issues the C1 command. However, this modem does not
support the C0 command. The C0 command may instruct some other modems to not send carrier
(i.e., it puts them in a receive-only mode).
C0:
C1:
ECG021/1298
Selects CCITT V.22 mode when the modem is at 1200 bits/s.
Selects Bell 212A when the modem is at 1200 bits/s (default).
Deselects V23 reverse channel (same as B3 ).
Deselects V23 reverse channel (same as B2 ).
Selects V.21 when the modem is at 300 bits/s.
Selects Bell 103J when the modem is at 300 bits/s (default).
n = 0, 1, 2, 3, 15, 16
Otherwise
Transmit carrier always off.
Normal transmit carrier switching.
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