350-801 · Question #255
An administrator executes the debug isdn q931 command while debugging a failed call. After a test call is placed, the logs return a disconnect cause code of 1. What is the cause of this problem?
The correct answer is D. The dialed number is not assigned to an endpoint. ISDN Q.931 cause code 1 is defined as 'Unallocated (unassigned) number.' This means the number dialed does not correspond to any endpoint or circuit that the network recognizes - the dialed number is simply not assigned. This is different from a busy condition (cause code 17)…
Question
An administrator executes the debug isdn q931 command while debugging a failed call. After a test call is placed, the logs return a disconnect cause code of 1. What is the cause of this problem?
Options
- AThe destination number rejects the call
- BThe destination number is busy
- CThe media resource is unavailable
- DThe dialed number is not assigned to an endpoint
How the community answered
(16 responses)- B6% (1)
- C6% (1)
- D88% (14)
Explanation
ISDN Q.931 cause code 1 is defined as 'Unallocated (unassigned) number.' This means the number dialed does not correspond to any endpoint or circuit that the network recognizes - the dialed number is simply not assigned. This is different from a busy condition (cause code 17), a call rejected by the destination (cause code 21), or a media resource issue (which would appear as an internal UCM error, not a Q.931 cause code). When troubleshooting, cause code 1 typically points to a dial plan or number assignment error on the PSTN or remote side.
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