504 Gateway Timeout after about 20 sec of ringing

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Jan 22nd, 2009
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I have a Cisco 2811 (IOS: 12.4(3g)) on which I do some SIP application development. The device is set up as an ISDN-SIP gateway.

The issue is that if I let the outgoing call to ring for more than about 20 sec, the gateway responds with 504 Gateway Timeout and disconnects the call. The call is triggered by a SIP INVITE that I generate and everything works fine if I answer the call earlier than this timeout. I checked the logs and there is no ISDN or SIP event that triggers the 504 Gateway Timeout - it seemingly comes out of nowhere.

Do you have any idea what can cause this timeout? Do you have any advice how I can obtain more information about the cause (e.g. more logging?)

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gaborpaller Tue, 01/27/2009 - 09:19
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Eventually I solved it.

The INVITE triggering the call was slightly erroneous. It contained a Supported: 100rel header when actually there was no such support. The PRACK timeout is 500 msec and after 11 retries, the gateway terminated the call.


debug ccsip error

log provided the clue.

*Mar 5 00:25:28.964: //1435/453DA1E084A5/SIP/Error/act_sentrel1xx_wait_prack: O

ut of retries state:11


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