Avaya VPN phones - intermittent voice issues

[JJLarue]

Hi all-

I'm a CM user, running 5.2. I have several VPN phones deployed to remote users, both 4610SW and 9650. Using Cisco ASA5510 for the firewall. All VPN phones register up just fine and grab DHCP from the 5510.

The problem I'm having is, when a VPN user calls into the main office, they can't always hear them. Sometimes, it will be one-way voice. Other times, no voice at all, and sometimes it works perfectly. This problem only seems to happen when the users 4-digit dial. It can happen when the call is made from in-house to VPN user, as well as VPN user to in-house, so direction doesn't seem to matter. I've been doing some testing in my lab, and I have a VPN phone and a TDM phone connected side by side. The test I've been doing is to 4-digit dial in rapid succession between the two phones and see if I have voice path. Seems like it works fine about 75% of the time, then there will be no voice path the other 25% of the time.

This is driving me crazy. Is this just the nature of VPN phones, or should it be working closer to 99% of the time? Any ideas what's happening here? What settings can I check?

Thanks.

 

[DAVIDPAYNE]

You need to do a list trace of the station and capture an bad call, and see if there is some sort of error code. If you can reproduce the issue then you should be able to get the trace.

 

[JJLarue]

Update on this issue. We changed the codec to G729B and that seems to have solved the problem. Seems like the VPN phones prefer G729B instead of G729. Seems to work for both 46XX and 96XX phones.

So now you know, in case any of you run across this problem in the future.

 

[avAyATEKky]

I have a question, I am trying to move towards 9650 VPN and I have the phones set for VPN enable. My site uses checkpoint did you have to get the vpn default gateway file to upload it to the phone to authenticate the certificate.

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