Fault Isolation For Subscriber Lines; Subscriber Lines Maintenance; Manual Lines Testing - Nortel DMS-100 Series Maintenance Manual

9-24 Trouble isolation and correction

Fault isolation for subscriber lines

Subscriber lines maintenance

Lines maintenance for the RCS consists of the following areas:
Line circuits, subscriber loops, and stations are tested under the lines
maintenance subsystem. Both the system and operating company personnel
test line circuits and subscriber loops in this subsystem.
Line testing helps determine if a line circuit, loop, or line circuit and loop
group function correctly. If the line proves defective, line tests determine if
the fault lies in the line circuit or in the attached loop. When a fault is in the
loop, the fault is referred to another department like plant maintenance.
When the fault is in the line circuit, operating company personnel must
replace the line card. You must test the line again to verify that the fault
cleared.
Line maintenance occurs under the following conditions:

Manual lines testing

The switch operator on line circuits, loops, and stations performs manual
line tests. Line circuits and loops are tested separately and the results appear
to the switch operator at a visual display unit (VDU).
297-8231-550 Standard 09.01 August 1998
commands issued from the LTP and automatic line testing (ALT) levels
line diagnostic initiated by a system diagnostic scheduler, a DMS-100
software process that occurs when a call fails twice
subscriber station tests
line tests executed through a mechanized loop tester (MLT) or test desk
facility.
the user enters a command from the LTP level
tests are scheduled from the ALT level
digit reception is defective. This defect causes the DMS switch to test a
line automatically for foreign potential
a call fails twice. This condition causes the system to place the call in
the shower queue for full diagnostic testing
the subscriber telephone set initiates tests
a test desk initiates tests
Note: Manual lines are tested as part of routine maintenance or when
the system generates a customer report or an ALT failure occurs.