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Troubleshooting Notes
When a system places or receives an ISDN call, the events during the call sequence
generate diagnostic codes. The Q.850 standard defines these codes.
The ViewStation EX, ViewStation FX, and VS4000 systems capture some of these
cause codes — such as the reason for call disconnection — in the Call Detail Report.
Other codes cause the systems to display error messages. The Q.850 codes can be
used to isolate and diagnose unexpected system behaviors.
Q.850 Cause Codes
The following table describes codes that the ISDN switch sends to the router to
indicate call status. Although the codes are standardized, each ISDN service
provider defines them differently. Because of this, the definitions in the table may
not exactly match the messages that you see.
Code Cause Definition
1 Unassigned number The switch received the sent ISDN number in the
correct format, but no destination equipment uses the
number.
2 No route to specified
transit network
The ISDN exchange does not recognize the
intermediate network through which to route the call.
3 No route to
destination
The intermediate network through which the call is
routed does not serve the destination address.
6 Channel
unacceptable
The specified channel does not provide adequate
service quality to accept the requested connection.
7 Call awarded and
delivered
The user is assigned an incoming call that is being
connected to a call channel that has already been
established for this user and this type of call.