User`s manual

U.S. Robotics I-modem Command Reference
Testing • Page 14-3
1. Send the command AT&M0&N3S14.0=0 to prepare the I-modem for testing.
This command disables error control, Þxes the connection rate at 2400 bps, and makes
the I-modem return to Command mode
when you type +++.
2. Establish a connection with the remote device.
3. Send the I-modem the +++ escape code to bring it back to Command mode.
4. Send the I-modem the AT&T3 command. The I-modem enters digital loopback mode.
5. Have the remote user type a short message. It will be looped back by your I-modem's
transmitter for veriÞcation on the remote userÕs screen. You will not see the message or
any other data.
6. When the remote user has completed the test, send the escape code, +++, and then
AT&T0 to end the test.
Alternatively, you can end the test by sending ATH, ATZ, or ATZ! Be careful, though,
because ATZ and ATZ! reset the I-modem in addition to ending the test.
In any case, the I-modem responds OK. If the I-modem sends an ERROR message, you
have issued an invalid command.