Call disconnect

Unanswered Question
Mar 21st, 2007
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Hello all;


I have CM ver 4.1(3) with a gatekeeper trunk connecting it to a PGW system for PSTN interface.


when placing calls from an IP Phone to PSTN sometimes (randomly) the call last for only 26 secs, and when I checked the CDR file of the call I found that the disconnect reason is 47 (Resource unavailable, unspecified) and it is the same value for dest and orig. what do u think the reason could be for this issue??

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walidazab Wed, 05/16/2007 - 04:03
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Hi,


When a Cisco IP Phone is unplugged, no immediate, physical indication goes to the Cisco CallManager.


The Cisco CallManager relies upon a transmission control protocol (TCP)-based keepalive signaling mechanism to detect when a Cisco IP Phone becomes disconnected.


Each Cisco IP Phone sends a keepalive message to the Cisco CallManager at the configured keepalive interval (default=30 seconds), and the Cisco CallManager responds with an acknowledgement. Both parties then know that the other is functioning properly. When a Cisco IP Phone is unplugged, it fails to

send this keepalive message. The Cisco CallManager waits twice the keepalive interval from the time of the last keepalive message before assuming that the Cisco IP Phone no longer functions.


Now the implication to billing is that, when a Cisco IP Phone is unplugged, the duration of the call that is reflected in the CDR can be up to twice the keepalive interval plus the TCP retry timers longer than the actual speech-time that the user experienced. This worst-case value assumes that the other party did not hang up.


Identify calls that fail in this manner by a cause value of 41 (Temporary Failure). This cause value can possibly occur in other circumstances because external devices such as gateways can also generate this cause value.


I hope this helps

Walid

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