Call Preserve

Unanswered Question
Jul 14th, 2008
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Morning guys an girls! :)

I wonder if anyone could shed some light on the call preserve feature under the voice class h323, I wanted to test if when failing between call managers using the h323 protocol whether when using the call preserve command would it preserve the call, and well it didnt.

I configured an access list to block me from the sub so that i would be forced to re register with the pub but the call still dropped. any ideas?


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Ayodeji Okanlawon Mon, 07/14/2008 - 03:05
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For you to have call preservation with an H.323 gateway you need to configure the following:

voice service voip


no h225 timeout keepalive.

This ensures that when TCP connection to callmanager is lost active calls are preserved

hellspire69_2 Mon, 07/14/2008 - 04:03
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I was under the understanding that, that particular command was for SRST fallback rather then call manager to call manager?

I was under the impression that for the cm to cm, the call preserve command was what actually needed to be set.

after testing the call preserve command and the no h225 timeout keepalive command neither work :(

hellspire69_2 Mon, 07/14/2008 - 05:24
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Ok i resolved the issue, the call preserve call does work but only in conjunction with the call manager parameters being set correctly, under the system parameters.

Thanks guys!

Ayodeji Okanlawon Mon, 07/14/2008 - 05:26
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What parameters under call manager?

Can you share here?

Can you also share the full config for the call preserve command..

hellspire69_2 Mon, 07/14/2008 - 05:44
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after you have entered the "call preserve" command under the, voice class h323 "number". you then have to amend the Service Parameters under the CM under the advanced tab, Allow Peer to Preserve H.323 Calls* <--- set this to true.

then you enter the voice class h323 "number" under the particular dial peer.. pots... etc..

or you could do the call preserve command under the voice service voip command to affect all calls :)

Thanks ^_^

Frantisek Opravil Tue, 02/24/2009 - 23:42
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And what about CallManager 5+, 5.1.3 in my case. There is no "allow peer to preserve H.323 calls" param in Clusterwide Parameters (Device - H323)?

Does CUCM 5.1.3 support "H.323 VoIP Call Preservation" at all?


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