Hi, I am not able to call extension to extension. I am however able to call using a trunk from those particular extension. I am using Zoiper in mobile and pc to try to test the calls. I keep getting this error message in the sip log 901@192.168.1.12:40409;rinstance=ab35de7621326849;transport=U' is not a valid SIP contact (missing sip trying to use anyway Please help someone