Hi, I know, the problem has already been raised but visibly it has not been solved. I've installed the latest 3CX Phone System 6.1 with an EyeBeam (X-Lite) client and a Siemens C470IP. I've two VOIPBuster accounts (only out), and one at freephonie.net (in and out) The MediaServer is reporting no RTP on freephonie.net where there is no problem with VOIPBuster. MediaServerReporting::RTPReceiver [MS105000] C:19.2: No RTP packets were received:remoteAddr=188.8.131.52:30210,extAddr=myExternalIp:9010,localAddr=myExternalIP:9010 Direct access to the SIP account from either EyeBeam or C470IP is working. What could I check to try understand what's wrong? Regis PS. it seems that 3CX PS 3.x is working with SIP accounts at freephonie.net.