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New Member

G729 calls to voice gateway bad... G711 calls ok.

I've got a few voice ios gateways with phones attaching to them over a vpn.

they are all 2651s...

Version 12.3(11)T2

Version 12.3(11)T7

Call quality from the phones on the vpn sound much better with G711... no dropped packets, every thing sounds great.

on G729 calls... I'm getting tons of dropped packets, blips and noise in the conversation and is basically unusable.

Any ideas of where I should start looking?

It seems counter-intutive that the g711 calls would have NO dropped packets and sound better over a non-qos enabled wan service like a VPN.


New Member

Re: G729 calls to voice gateway bad... G711 calls ok.

We had a similar issue with calls coming in from PSTN via PRI that were encoded G729. We would hear "robotic, metallic, unintelligible" sounds.

The problem was intermittant, and I eventually traced it to G729 calls that were being processed by one particular DSP.

What is the call flow in your situation? Are the calls going out to the PSTN?

New Member

Re: G729 calls to voice gateway bad... G711 calls ok.

yup... calls outbound to the pstn.

however, it happens on all our gateways. not just one.

and users..

it might be related to:

Strip G.729 Annex B (Silence Suppression) from Capabilities*

I changed that to True in the cluster-wide parameters.

We're testing right now to see if that helps.