AT&T System 25 - Manual (Page 266)

MAINTENANCE
Trunk Troubles
Many trunk troubles originate in the central office
(CO)
facilities. The first step
in identifying trunk troubles should be to check for presence of dial tone at
the Trunk Access Equipment (TAE). If required, check the Error Log records,
and make a trunk test call.
Note that it is sometimes difficult for the user to detect or identify trunk
troubles. If an outgoing trunk is down, an error is recorded in the error log
and the trunk is taken out of service (see Note ). If an incoming-only trunk is
down, however, the only indication of trouble is customer complaints that
incoming calls are not being received.
Note: For Release 1, Version 2 or Release 3 systems, the system
will not busy out more than half of the trunks in any pool.
Thus, a permanent alarm may be logged against a particular
trunk, but the trunk may not be taken out of service because
.
of this constraint.
Other troubles could occur because of incorrect loop current. The loop
current of trunks from the CO to System 25 should be 20 mA.
Outgoing Trunk Problems
Symptoms:
Difficulty in seizing outgoing trunks.
P r o c e d u r e s :
1.
2.
3.
4.
Verify that dial tone is received from the CO at the TAE (see Note).
If dial tone is not present, notify the CO through the proper channels.
N o t e : For ground-start trunks, apply ground to the Ring
lead to get dial tone.
Go off-hook at a test
Dial *2 (the test code
Dial the 4-digit trunk
same number used
trunk.)
station to get system dial tone.
for all non-DID facility trunks).
number of the trunk to be tested.
by the System Administrator to
(This is the
identify this
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