We are running 2 Asterisk boxes (ast-a and ast-b) connecting our 2 offices. We did some voice quality testing as follows: ast-b calls ast-a externally (ie. over public phone lines), ast-a forwards the call back to ast-b over IAX. Since ast-b can't access the public phone network by itself it has to talk to ast-a over IAX to reach public phone lines that way. So the external phone-call really looks like this (dialing external number of ast-a at ast-b): ast-b [ IAX ] ============> ast-a [ public phone network ] ^ | | | -------- Then ast-a transfers call to a different extension at the ast-b location (over IAX). So we have: ast-b => [IAX] => ast-a => [ phone network ] => ast-a => [IAX] => ast-b We discovered the following pattern of noise on the line: after about 4 minutes 45 seconds there'll be tiny interruptions in the transmission for about 4-5 seconds, after that it would be ok for about 1:35 at which point another 4-5 second disruption occurs. Then it would start all over again. Transmission ok for 4:45, disruption, transmission ok for 1:35, disruption, ... So that follows a pattern. Any ideas how to find out what exactly is going on here and which box is tropping/losing packets or if it happens somewhere in betweeen (hops we can't control)? Best regards, Markus