Hi all and thanks for reading. I am experiencing a frustrating issue with asterisk where on some calls the volume suddenly drops to inaudible o completely fades away for a time. If you hold on long enough (20 to 30 seconds) the sound will come back. My asterisk server is on a public IP, and basically acts as a VoIP bridge receiving calls from my customers (all of whom use Grandstream GXW400X gateways on public IP's, no NAT) and sending them to different SIP providers. I am proxying the RTP stream through the server (canreinvite=no). I am sure this is an issue with my setup because this happens to random customers calling to random destinations on any of our VoIP providers. The symptoms are always the same: voice becomes inaudible or fades away, most of the time the customer hangs up. I am running CentOS 5.5 and asterisk 1.6.2.15 on 4 different servers, all of them Dell PowerEdge. Any ideas? I do not even know how to start debugging this issue. A SIP trace obviously shows nothing. Any pointers would be appreciated. Regards, Alex