This section lists the command and control codes for popular modems. Most modems use a standard
AT command set that was developed by Hayes and augmented by U.S. Robotics. Table 27
comes in handy when you need to reconfigure a modem without the original manual. Even if
your modem is not Hayes or U.S. Robotics, it probably follows most of these commands because
this command set has become somewhat of a standard. S-register values listed at the end of the
table are also somewhat standard but are more subject to variation in the defaults by brand and
model.
Table 27 Modem AT Commands and S-Register Features
Command Modem Functions and Options
& See Extended Command Set
% See Extended Command Set
A Force Answer mode when modem has not received an incoming call
A/ Reexecute last command once