I've solved this problem. It was very easy (only if I knew how to do it before). I changed the UDP ports, i.e.<br><br>1. In sip.conf, bindport=5070<br>2. In my IP Phone server settings, <a href="http://www.myserver.com:5070">
www.myserver.com:5070</a><br><br>Now it seems to be working good and I hope there'll be no more problem with it.<br>