Polycom VSX 3000 Administrator's Manual page 196

Administrator's Guide for the VSX Series
Appendix - 10
Code Cause
127 Interworking,
unspecified
145 ISDN layer 1 and/or
2 link not
established
146 ISDN layer 3
connection to the
ISDN
switch/network
inactive
255 ISDN command
processing error
Definition
An event occurred within a network that does not
provide causes for the action that it takes. The
precise problem is unknown.
User needs to check cabling, ISDN adapter status
and network connections.
There is either a switch protocol error, or (in the
United States or Canada) a SPID assignment
problem.
The ISDN signaling code has encountered an
error processing an ISDN action. ISDN adapter
busy-wait and retry.