Appendix E: AT Commands
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Appendix E: AT Commands
AT commands communicate directly with the modem when it is in
command mode. This appendix is a quick reference for
experienced modem users. We do not recommend that you use
AT commands unless you are familiar with them. It is possible to
disable your faxmodem inadvertently.
To summarize AT command syntax:
Q
Multiple commands can be strung together in one line.
Q
Command lines cannot exceed 40 upper- or lower-case
characters. (Do not mix upper- and lower-case.) The modem
ignores space and hyphen characters.
Q
Command lines must start with AT and end with a carriage
return (Return or Enter).
Q
A missing command parameter is assumed to be a zero. For
example, ATH is the same as ATH0.
Q
A/ on a line by itself without a carriage return causes the
modem to repeat the previous command.
To switch to AT command mode from data mode, wait at least
one second, type
+++
(the default escape characters), and wait
at least one second before entering other characters. After the
OK message from the modem, you can enter AT commands. To
return to data mode, type
ATO
and press Return (or Enter).
AT commands for SVD (simultaneous voice and data) operation
are located on page 26.
Bold indicates the default setting. (Not all commands have defaults.)
Command
Function
A
Answers incoming call immediately
B0
B1
Uses V.22 connection at 1200 bps
Uses Bell 212A connection at 1200 bps
D
n
Dials telephone number
n
You can combine D with one or more of the following modifiers:
L
Redials last number
P
Uses pulse dialing
T
Uses tone dialing
R
Command accepted but not acted upon.
S=
(0-3)
Dial one of 4 numbers stored with &Z
n
!
Goes on hook (time specified in S29)
W
Waits for dial tone
