I have a TDM2400P installed but I don’t think that the make of the card really matters for this problem, I could be wrong. In my dialplan, I have an extension that forwards to a different number if the number being called first doesn’t answer. The problem is that once the first call is not answered, and asterisk goes to forward the call out, the volume of the call drops dramatically, almost to the point where you have to have the caller shout to be heard at the other end.
I have rxgain=8 and txgain=2. It is only on calls that are bridged from one fxo to another fxo channel. No problems with any calls from SIP extensions and I did not notice anything wrong with calls from fxs (analog phones) to fxo. Faxing is OK too. I will try to forward calls through voip provider instead of POTS, just to see how it will work. I will post config later if I don?t solve this problem tonight.