PSTN calls always use g729

Answered Question
Dec 9th, 2008
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I know g729 is for VOIP calls to make good use of bandwidth and I know that PSTN (E1 or T1) should use g711 since they are un-compressed. But in my CM 4.1(3) setup, all my calls via PSTN (incoming and outgoing) use g729, even if my IP Phone and the H323 gateway are in the same Device Pool, hence using the same Region. Any thoughts?

Correct Answer by Jaime Valencia about 8 years 7 months ago

that's dial peer, region and phone capabilities config. make sure the DP is set to G711 and the region is G711. if no avail you'll need to look at a CUCM trace to see why it fails


HTH


java


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Jaime Valencia Tue, 12/09/2008 - 12:30
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PSTN links are always PCM, the G729 can only go as far as your router. only if you use a SIP trunk you could have G729 end to end. the router should be changing the streams.


if you have not defined a codec or voice class codec under voip dial-peers G729 is the default codec.


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junp14 Tue, 12/09/2008 - 12:43
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java, thanks.


Sorry if I didn't made myself clear. My question actually is: Why PSTN calls always use g729? I have voice-class codec in my VOIP dial-peer and I have g711 as the preferred codec but still PSTN calls use g729. If I hard code g711 only in my VOIP dial-peer, calls drop. Any idea how I can make PST calls use g711? Thanks.

Correct Answer
Jaime Valencia Tue, 12/09/2008 - 12:45
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that's dial peer, region and phone capabilities config. make sure the DP is set to G711 and the region is G711. if no avail you'll need to look at a CUCM trace to see why it fails


HTH


java


if this helps, please rate

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