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New Member

How to really disable VAD ??

there is an issue with the voice quality during _some_ external calls.

the beginnings of spoken words are being cut off.

It sounds like VAD with thereshold-issue.

It is really hard to understand the speaker...

the problem is that VAD is disabled.

the gateway is a 3660 with IOS Version 12.2(7b)


New Member

Re: How to really disable VAD ??

Are you sure that VAD is disabled? You have to disable VAD on both call legs on the gateway for each dial-peer and also on Call Manager.

You can verify VAD is disabled on the gateway by looking at the output of show voice call summary.

On the Call Manager(s) look at the CCM Service Parameter for each Call Manager server. You want "Silence Supression System Wide" and "Silence Suppresion With Gateways" set to false on each Call Manager Server.

Hope this helps.

Tim Medley, CCNP+Voice, CCDP, CWNA

Sr. Network Architect

VoIP Group


New Member

Re: How to really disable VAD ??

Is there really a callmanager involved?

Turn on debugs (ie. debug voip ccapi inout) to verify which dial-peer tag that the calls in question are matching. Make sure VAD is diabled on those


Also, What codec are you using? Try G711ulaw and retest calls. If you are

using G729, VAD is built into the codec and is always used.

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