User`s guide

Test Mode Operation
7-6 Modem 3600
Grant/Deny RDL Request &T4, &T5
Local operators can deny a request from the remote modem for remote
digital loopback.
To allow your modem to be placed in RDL by a remote operator, enter
AT&T4
To prevent your modem from entering RDL, enter
AT&T5
Remote Digital Loopback &T6
The initiating modem signals the remote modem to go to Digital
Loopback. The remote modem receives and then retransmits data back
to the local modem. If Digital Bilateral Loopback is enabled on the
remote modem, the remote DTE is looped back to itself (Figur e 7-4).
Figure 7-4. Remote Digital Loopback with Digital Bilateral
Loop Enabled at the Remote Site
After making the data connection, enter the escape sequence to return to
command mode. Entering &T6 places the remote modem in digital
loopback provided the remote operator has entered the &T4 command
to allow an RL request. Enter a test message and verify the message is
being looped back to your terminal screen. If the message is incorrect,
use the analog loopback tests on both modems to isolate the problem. If
both modems run analog loopback without errors, the problem could be
with the phone line.