calls dropping after 5 mins

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Mar 16th, 2009
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I have a client that says the srst gateways are dropping pstn calls after 5 mins, client recently did upgrade to 7.0 CM suspect the routers may have needed up grade as well? not sure of all issues yet I will be doing a q&a on Wed with client. Just asking a preliminary question for now on gateways thanks to all repies

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gogasca Mon, 03/16/2009 - 17:49
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When u say SRST GWs, the IP Phones r in SRST mode, or GWs just acting normally register to CUCM or H323?

5 minutes looks like a timer,

find out if there is any security device in the middle and type of GW.

We have seen this normally when there is a firewall which closes TCP h245 connection.

Please let us know more details


bmarlin Tue, 03/17/2009 - 06:57
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I had suspect timing issues but I wanted to rule out gateway as well. Did an upgrade to a different system which went to 6.1 we had to also upgrade srst GW image,I should know more by tomorrow from Q&A with client

thank you I will keep you guys informed.

bmarlin Fri, 03/20/2009 - 08:15
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Suspected timers and originally all indications at client site showed this,

made some h323 h225 timer changes to both router on and call manager with no change ,phone calls still lasted 5mins 15 sec.

Changed all setting back in gw and CM and starting debug on h225 instead of q931 and q921 debug.

Call control was not able to pass thru FW.Find this by debugging remote router h225 and saw the tcp ack return packet getting hammered each time it tried ack to CM lasted 5 mins 15 secs (CM timers).

Questioned client, found out that there was a Firewall upgrade to all 4 sites that had changed how the ASA did inspection on h323.

Had firewall all allow exception on h323 inspection to allow call control h225 and everything functioned normally.

Thanks for all the suggestion there helped in determining trouble.


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