Using a 2811 as h323 gateway. All was working fine until a few days ago. OUtbound and inbound calls on Verizon PRI started to have a tinny sound. IP phone to IP phone internally has exceptional voice quality. Only outgoing and incoming calls from PRI have a tinny sound. Can anyone shed some light on what maybe causing this? Thanks.
Generally speaking audio problems come from five places:
1) Your Endpoints
2) Your DSPs
3) Your IP Network related problems.
4) Interference/noise/echo from your analog lines
5) Other people's DSPs/networks/endpoints
1) You can try upgrading the Cisco phone firmware. Since this firmware was working, I don't expect this to be the problem. Maybe the users upgraded to wireless headsets?
2) This really requires TAC to find out. Your DSP firmware version should be fine though in 7g. Sometimes replacing DSPs will solve audio problems, but not nearly as often as people believe.
3) The jitter values and packet loss are good. If the latency is below 150ms, you should be fine
4) Hard to tell - you can try switching known good lines with known bad lines. See if good calls go out one T1, but bad calls go out another. Sometimes you don't have this luxury.
5) My least favorite. Providers can be very bad about admitting problems on their lines. They will generally send an engineer out, he'll make a couple of test calls with a butt set, and that's the end of it. Better hope your problem happens often.