Apple Express Fax/Modem - Manual (Page 127)

Commands documented in this appendix
This appendix documents the command set recognized by the Express
Modem. The command set is compatible with the V series Hayes AT
command set, a subset of the Microcom AX series MNP command set, and
the class 2 TR-29/89-21R7 AT+F Fax extension set. This document does not
describe the Fax AT+F subset.
Integrated (non-serial port) modems
Traditional modems—external modems or even modems that plug into a slot
on a main logic board—use an RS-232-like serial connection protocol
between the CPU (Data Terminal Equipment–DTE) and the modem (Data
Communications Equipment–DCE). Your modem does not use this type of
serial connection.
Since your modem has no DTE-DCE serial interface, all commands related to
the serial interface have no effect. The commands themselves still exist for
script compatibility reasons.
Command set rules
The command line can contain any number of commands and their options
as long as the total number of characters, not including the attention
characters or the line termination character, does not exceed 64, the length of
the command line buffer. With only a few exceptions, described later in this
appendix, the command line begins with the attention characters AT and ends
with a return character, called a carriage return <CR>.
If the command line exceeds 64 characters, the result code ERROR is
returned and no commands are executed. If the number of characters is less
than or equal to 64, the commands are processed in order from the AT to the
<CR>. If a command is invalid or unrecognized, processing of the command
line ends at that command. Any commands following the error are ignored
and the result code is returned to your computer.
115 M O D E M C O M M A N D S E T