Ositech comm Trumpcard Data/Fax Modem - Manual (Page 85)

User’s Guide and Reference 5- 7
Modem Test Procedures
Local Digital Loopback
This test is used to verify the communications link and the remote
Modem, and is only functional when the Modem is in direct mode (&Q0)
and the COM port baud rate is set to 14400 bps (Trumpcard 14400) /
28800 bps (Trumpcard 28800) or less.
To run this test:
1. Establish a connection with a remote Modem.
2. Enter AT&T3 [ENTER] to put the Modem into the local digital
loopback mode.
3. Instruct the remote Modem operator to enter a message.
During this test the local Modem simply loops back any incoming
data to the remote Modem. If the information sent and received by the
remote Modem are identical, the test is successful.
4. Enter AT&T0 [ENTER] to end the test.