Philippe, The audio is sent through UDP packets, not TCP packets. The main difference is that if UDP packets are lost in collisions or congestion, they are not retransmitted. What you are describing COULD be completely explained as internet congestion. I would test with some application that loads her network link down. One example is <http://www.onsip.com/tools/voip-test> http://www.onsip.com/tools/voip-test Try the various levels (1 line, 3 or 5 lines) and see how a call with her reacts when the test are run. That will at a minimum rule out congestion on her local internet connection. HTH, Sean From: freeswitch-users-bounces@lists.freeswitch.org [mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of Philippe Le Toquin Sent: Tuesday, April 23, 2013 4:12 PM To: FreeSWITCH Users Help Subject: [Freeswitch-users] advise to troubleshoot a call Hello, Recently I (well my wife) is having voice problem when she is on a call. Typically she can hear people but they can't The problem is that it is not all the time and when it happens it last a few seconds then all back to normal... then later on it happens again. I am still in the process of trying to find if there is a pattern in the problem but I would like to be able to look at the log from FS. What would you recommend to be able to look at the log (what debug level). Any tips to make it easier to identify an issue in the log (like message to look for?) Thanks Philippe