We have two TG800 devices, both with same versions:
.. And we are having sound quality problems with calls between the GSM phones and VoIP devices.
Sound quality is not that good to start with, but during the call sound kind of fades away and then comes back, just to fade again.
There's not that much traffic in the LAN, so I think the problem is somewhere else. Also switching between codecs does not seem to have any effect, so far I tried GSM, aLAW and uLAW, as these are natively supported by our VoIP environment.
I have tried calling to phone connected to our Asterisk, also to a phone connected straight to the TG800, the problem is always there.