User`s guide

AT Commands
Modem 3600 5-25
Return Online O
Use the O command when you are operating in the online command
mode and need to return to data mode. It returns the modem to the same
mode (originate or answer) that it was in before escaping to the (online)
command mode. Enter the O1 command to cause a retrain to occur
before going back to data mode.
Long Space Disconnect Y
One method of disconnecting two modems is called long space
disconnect. When any disconnect condition is detected by the local
modem, it will send 4 seconds of data space condition to the remote
modem before disconnecting. This signals the remote modem to
disconnect. The local modem will disconnect if it receives 1.6 or more
seconds of data space condition from a remote modem. If break
sequences of 1.6 or more seconds are to be sent, enter the Y command to
disable this feature and prevent unintentional disconnects.
Note
This option must be disabled if SDLC NRZI data is used.
V.22 bis Guard Tones &G
Guard tones are not used in the United States. If required where
operating the unit, select the appropriate guard tone.
Asynchronous / Synchronous Mode Selection &M
The &M commands select synchronous or asynchronous operation and
synchronous dial method.
Command Operation
Y Long space disconnect off
Y1 Long space disconnect on
Command Operation
&G No guard tone
&G1 550 Hz guard tone
&G2 1800 Hz guard tone