I have a setup using a UC560 and ~25 SPA504G phones using a quality T1/PRI line. All are upgraded to the latest software/firmware. I have a user complaining that the phone quality is muddled and I'm wonder what would be the best way to diagnose and fix this problem.
1. Ensure that the phone's firmware is upgraded to the latest version
2. Change the handset (I've had another user with a faulty handset)
What steps should I follow after this? Are there different audio codecs that can be selected per phone or other tuning that can be done?
The volumen and the codec. Try having only codec G.711 ulaw (I guess you are in the US because of the T1). Disable the rest. The problem may be that you have too many calls at the same time. You may try with only 1 call and then with many, if that is the case try G729 as the preferred (uses less bandwitdh)
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