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Cisco Bug: CSCtf04533 - MGCP leaked calls due to outbound gateway failure

Last Modified

Feb 22, 2014

Products (1)

  • Cisco Unified Communications Manager (CallManager)

Known Affected Releases


Description (partial)

Calls to an MGCP T1 CAS trunk fail because CUCM thinks that all channels are busy.  Individual perfmon counters as well as router 'show' commands will indicate that there are idle channels.

Calls get stuck active when an outbound call fails for some reason, resulting in an MGCP NTFY message getting sent to CUCM with the line 'O: DT/of(dt/sup)'.  This means an operational failure occurred during the processing of a call setup.

One possible cause is a new call getting sent out the same port that just disconnected a previous call and the far-end device is not ready for the new call.  This can easily happen if a call is attempted but not completed as the CUCM RouteList only considers a call that gets to a connected state when doing a circular call routing algorithm.

You can verify these call leaks by looking at the perfmon counter CallsActive for the MGCP gateway in comparison with individual channel busy status.  If callsActive is 23 but no channels are actually busy then CUCM will not route any further calls to the gateway as it thinks it is busy.
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