Remote Digital Loopback with Self Test - &T7
This test verifies operation of the local modem, the remote modem, and the
telephone circuit. The local modem sends a self test pattern to the remote
station. The remote modem, when configured to grant remote digital loopback
(with &T4), loops its receive data stream back to the local system.
The local modem examines the receive pattern and increments an internal
error counter each time an error is detected.
Note: This test may be performed with a V.22 or V.22bis connection
and &Q0 mode selected.
Step 1:
Establish a connection with a remote modem. Then, enter the command
state and initiate the remote digital loopback by issuing &T7.
Step 2: When the test is terminated with the &T0 command, the modem
returns a three-digit test result (e.g., 000=no errors; 012=12 errors).
If the error count reported is 000, the local and remote modems and the
telephone circuit passed the test. If errors were encountered, initiating
a local analog loopback test further isolates the problem. An error count
of 255 indicates that 255 errors or more errors were detected.
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