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voice is choppy the first 1-5 seconds.

I have CM 3.3.2 SPB. The calls come in on a 3640 MGCP gateway. Out of about 30 calls per hour, there are about 10 calls that start out with choppy voice. After about the first 1-5 seconds, the call is OK. This happens mostly at the main site, but the remote sites get it also. VAD is disabled on all the routers. The routers are running 12.2.2. Any ideas?

2 REPLIES
Cisco Employee

Re: voice is choppy the first 1-5 seconds.

You are probably hearing the either the echo cancellor converging or the playout-delay buffers adjusting to what jitter is there. Try a call and look at the output of show call active voice, if you see playput delay buffer overruns, predictive conceal, or interpolated packets in the stats(more than single digits), its the de-jitter buffer and can be adjusted with the playout-delay commands. If not it is probably the ecan and you can tweak it with the echo-cancel suppress command:

http://cisco.com/en/US/partner/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml#echosuppressor

Hope this helps...

New Member

Re: voice is choppy the first 1-5 seconds.

I have had this problem a lot with 2651xmv routers and found that if you run the latest code and set the echo cancel to 64 if you have not done so already. The default in Cisco IOS Release 12.3(4)T and later is 64. You must also use the echo-cancel enable. There is one more thing on the version of cm you are running you can only tweak the echo cancel to 32, in 3.3.3 you can go to 64. It is ok to leave it at 32 in cm manager. Hope this helps.

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