ATT System 25 Installation And Maintenance Manual

MAINTENANCE
2.
3.
4.
If you hear dial tone, continue with this test.
Dial the digits 1234567890 *#.
Y
OU should hear a DTMF signal as each key is pressed.
If the test passes, you will hear dial tone within 1 to 3
seconds after you enter #.
Repeat the test for each touch-tone receiver.
Replace the Service Circuit CP if this test fails.
7300H Series Terminal Troubles
Symptoms:
7300H Series terminal LEDs and/or tones not functioning properly.
Procedures:
1.Move the T/P lever on the left-hand side to the “T”...

MAINTENANCE
Procedures:
1.Make sure that the appropriate ZTN79 CP is translated.
2. Check for the presence of -48 volts at test point on front of cabinet.
Symptoms:
Inoperative
used.
Procedures:
1.If LOCALdisplay-equippedvoice terminal when LOCAL button isbutton/lamp
activate LOCAL button.is off, and voice terminal is inoperative,
2. If terminal is still inoperative, check for other problems.
Virtual Facilities Troubles
Refer to Figure 4-12 for assistancein clearing virtual facilities troubles.
4-85 

MAINTENANCE
Figure 4-12.Clearing Virtual Facilities Troubles (Sheet 1 of 3) 

MAINTENANCE
Figure 4-12.
Clearing Virtual Facilities Troubles (Sheet 2 of 3)
4-87 

MAINTENANCE
Figure 4-12.Clearing Virtual Facilities Troubles (Sheet 3 of 3)
4-88 

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...

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...

MAINTENANCE
6. If “no loop current on outgoing call” is displayed, either of the above
conditions could be true. It is more likely, however, that the facility is
down.
7.Place an outside call on the line using the trunk test call procedures
listed in outgoing Trunk Problems.If you get fast busy tone, switch
trunk ports and try again.
8. If the problem does not move, replace the Loop Start CP.
9. If the problem moves, the fault is with the CO. Notify CO personnel
through the proper channels.
Error Log...

MAINTENANCE
8.
9.
10.
11.
12.If the problem does not move, replace the Ground Start CP.
If the problem moves, the fault is with the CO. Notify CO personnel
through the proper channels.
If “Ringing no ground”is displayed, the T and R leads may be
reversed in the trunk access wiring. The T lead should have ground,
and the R lead should have –48 volts. These can be verified by
reversing the ground and ring leads and checking with either a
voltmeter or a test set (with a polarity switch). A voltmeter should...

MAINTENANCE
3.
4.
5.
6.
7.
8.
9.
l CO failure to release after PBX disconnect
l CO belated release.
These messages indicate CO problems. The first three errors are
very common when DID trunks are installed. The CO should be
notified through the proper channels about any of these problems.
The CO failure to release after PBX disconnect can frequently be
corrected by disconnecting and then reconnecting the DID trunk. If
this procedure does not resolve the problem, notify the CO through
the proper...