sundance-communications.com/forum Forums TDM Business Telephone Systems Panasonic Telephones & Systems IP Phone Quality Issues

I have a customer who has two office locations. The main office has a TDA100 system with the IP-EXT16 card in the PBX. They have around a dozen digital telephones and 1 IP telephone connected to the phone system. The other site has just 3 IP telephones. The remote site has been reporting terrible call quality for several weeks now. I have tried adjusting some settings in the PBX but there really is not much I can do. I have tried adjusting the codec. That didn't help. I have run speed, latency and jitter tests on the internet connection and they all come back within normal ranges. We have used the one IP phone at the main office for test calls and there is no quality problems on that phone. I am quickly running out of ideas. I can suggest that they get a faster internet connection speed at the remote office. Currently they have a 12M x 1.5M connection. Perhaps the slower upload speed is causing the issues. But I am not convinced of that as the speed tests all seem to come back just fine. So I am looking for any other ideas someone may have on something to test or try to narrow down the cause of the problem. They do have a VPN router at each site and those seem to be fine but is it possible one of those is failing? Or could some piece of hardware in the phone system be failing and need repaired or replaced? Any help would be appreciated.

What other traffic is moving between the two sites on the VPN?? If that traffic is heavy it would explain your issue.

They tell me the only other thing is they use a terminal server at the main office and the three users at the remote office connect via terminal server sessions. I don't know how much bandwidth that uses up though.

Take users off line and test calls.

Have you tried making calls between the two sites using a VoIP Tes tool?

Try and see if the quality is still poor.

If quality is okay, then the configuration or PBX becomes a suspect.

First try that

you are doing a speed test on broadband, but have you done tests down the VPN, like WTL said use the voip tool to see what the vpn is like.
if you change the ip phones to g729a, this will reduce the bandwidth but also make the sound quality poor

the upload speed will be a factor as using g711 will use about 80k when in use per phone.