AT&T System 25 - Manual (Page 267)

MAINTENANCE
5. Listen for dial tone from the accessed trunk. If dial tone is not
present, isolate the fault to a trunk port CP or location in the trunk
access equipment, etc., using a test set.
6. If dial tone is present, dial a working outside number. Verify that the
call is complete.
7. If trunk is busy, fast busy tone is heard. If a nonport trunk was
dialed, fast busy tone is heard.
Incoming Trunk Problems
Symptoms:
Incoming trunks (of any type) not working properly.
Procedures:
1. Place an incoming call through the troubled trunk.
2. At the SAT, check the trunk translations to be sure this trunk has
been properly translated. (See the Administration Manual.)
Error Log Interpretation: Loop-Start Trunks
Procedures:
1.
2.
3.
4.
5.
Check Error Log for messages pertaining to loop-start trunks.
If “no loop current on incoming call” is displayed, no loop current
was detected on an incoming call. The CP detected ringing, but not
loop current when it closed the loop. In this case, the CO facility is
probably good, but either the current sensor on the CP is faulty or
the CO battery circuit is faulty.
Switch trunk ports, and see if the problem moves to the new loop-
s t a r t t r u n k .
If the problem does not move, the loop-start CP is faulty and must
b e r e p l a c e d .
If the problem moves, the fault is with the CO. Notify CO personnel
through the proper channels.
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