User`s manual

U.S. Robotics I-modem Command Reference
Modes of Operation • Page 2-6
You can always switch the operating mode manually using one of these commands:
AT+FCLASS=0 (Switch to Data mode) <Enter>
AT+FCLASS=1 (Switch to Class 1 Fax mode) <Enter>
AT+FCLASS=2.0 (Switch to Class 2.0 Fax mode) <Enter>
If you are not sure whether the I-modem is in Data or Fax mode, type the following com-
mand:
AT+FCLASS? <Enter>
The I-modem returns a value of 0 to indicate Data mode, 1 to indicate Class 1 Fax mode,
or 2.0 to indicate Class 2.0 Fax mode.
Note Whenever the I-modem is reset using the ATZ or ATZ! commands, by tog-
gling the DTR signal or by turning the power off and then on, it will reset
to Data mode.