Multi-Tech Systems ISIHP-2U - Manual (Page 93)

MultiModemISI Hybrid Series, ISIHP-2S/2U/4S/4U/4SD 93
Modem AT Commands & S-Registers
the modem to enter command mode from online mode without
disconnecting the call.
+++AT<cr> In-Band Escape Sequence
If the modem is online with a remote modem, you can cause the modem to
enter command mode without disconnecting the call by typing an escape
code. The default escape code used by the modem is three plus signs (+++)
followed by the letters AT, up to 10 command characters (most typically H,
to hang up), and ENTER. The modem then escapes to command mode,
executes the command (if any), and remains in command mode. For
example, to hang up the modem at the end of a call, type +++ATH <cr>.
A Force Answer Mode
You can use the A command to force the modem into answer mode. Type
ATA when in command mode to immediately bring your modem off-hook,
out of command mode, into online answer mode, and to cause it to transmit
its carrier signal over the phone line. If no responding carrier tone is
received by your modem within 45 seconds (or by the time you specified in
register S7), your modem stops transmitting its tone, hangs up, and goes
back into command mode.
On Go Back Online
n = 0, 1, or 3
Default: none
Use the O command to bring the modem out of command mode and back
into online mode. The O command reverses the result of entering the escape
code. The O command brings modem into the online mode (originate or
answer) it was in prior to entering command mode.
O0 causes the modem to exit command mode and return to online data
mode.
O1 causes the modem to issue a retrain before returning to online data
mode.
O3 causes the modem to issue a rate renegotiation before returning to
online data mode.