Nortel Meridian 1 Planning, Installation And Operating Instructions page 552

Possible cause
Defective PE circuit
card
Defective Ringing
Generator
Option 11C Compact
Chapter 25 — Fault locating and clearing
Action
Software disable the telephone TN by entering
LD 32
DISU c u
("c u" represents card and unit number)
Disconnect wiring between the PE circuit card and the cross-connect
terminal.
Re-enable and test the TN by entering
ENLU c u
Wait for an OVD message. If you receive a message indicating a
problem with the circuit card or unit, replace the circuit card.
If you do not receive a message indicating a problem with the circuit
card or unit, reconnect the wiring and go to the next possible cause.
If several sets on different circuit cards in the same cabinet are
affected, replace the NTMW11 power supply in the cabinet.
Planning, Installation, Fault Clearing and CCBR Guide
Page 533 of 536