Ericsson ZAT 19.2 Operation Manual page 286

14.10 Digital loopback
The purpose of this test is to check local modem , the remote modem
and the line between them. This is obtained by looping the data flow
from the remote modem via the local modem back to the remote
modem. The remote DTE then compares the transmitted data with
the received data.
Remote
Modem Modem
| — Modulator __ Modulator ¢_ | __ |
__{,_|Demedutator Demodulator] | Los
Preconditions:
Your own modem must have established a connection with the
remote modem ( A-mode or B-mode ).
Test timer disabled - example 1:
=>Enter:
re ee
The modern returns to the command
: : ok, stale
The modem answers OK
= Enter:
&T3 Selects Digital loopback
Test indicator lignt.
The modem answers OK The test is in progress
When the remote operator informs (normally by phone) that the
test is completed, the test loop can be disabled:
= Enter:
AT&TOp*] &TO disables the test
The modem answers OK Test is terminated
1 4-1 6 LZTR104006 R1.00
Zat 14.4/14.4-7 and 19.2/19.2-7