I have a system setup with 8 grandstream xp-2000 phones and asterisk. The asterisk server has a 4 port digium tdm card installed. I have had tons of problems with the sound quality, everything is always two quiet, there is echo on the line when you first answer a call. If I up the rxgain and txgain setting I can get better volume but then the phones pick up tons of background noise.
I have another setup that is almost identical but with Cisco 7905/7912 phones and call quality is perfect. Any ideas? Also, I cannot find a description of the echo training setting anywhere. What does that do?
Any help would really be appreciated.