Northern Telecom M5317TX Installation Manual page 63

Also confirm that a terminating resistor is present in the loop,
when necessary.
If error codes >>21<< - >>2B<< are displayed, there is a possible
2.
TEI mismatch problem. Check that all TEIs defined on the set match
those expected by the network. Also confirm that no two sets on the
same loop have the same TEI.
3. If error codes >>31<< or >>32<< are displayed, confirm that all
SPIDs have been correctly defined on the set.
4. Replace or repair any defective wiring between the telephone and the
network termination or line card.
5. Confirm that non-reversing cables are used.
6. Substitute a different telephone, datafilling it with the same
information as the suspect telephone.
7. Replace the telephone and repeat the installation process.
Optional equipment
M5317TX and CustomNet Installation Guide
53