I have a new install of 3CX which is working fine - at most times. 3CX is installed on a standalone desktop pc, running windows 8 Installed version is V12.0.35528.640 Firewall is not active on the pc. Internet access is given by a Belkin ADSL router, this router also has firewall disabled. Using the firewall checker within 3CX all ports pass the test. When a customer calls our phone number, sometimes after the connection is made there is dead air/silent, no audio for the caller in. Then if they try again a few moments later it will work fine. When the call in has dead air the activity log always shows; [MS105000] C:16.1: No RTP packets were received:remoteAddr=xxx.xxx.xxx.xx:19880,extAddr=0.0.0.0:0,localAddr=xx.x.xx.xxx:9028 i have tried all methods described in previous posts in relation to this, all to no avail. I think it has something to do with the above "extAddr=0.0.0.0:0" is always zero's. The remoteAddr is my VIOP provider and the localAddr is my static ip from my ISP. Hardest thing to identify as sometimes it will work fine all day, then all of the sudden an incoming call will connect to our system but will hear no IVR or audio. Any help will be much appreciated.