Hello, I have a problem with my 3CX server (version 12): When I want to register an phone with the 3CX software on it, outside my house / LAN, it can't connect to the server. 3CX error log shows me the following error: registrar host <sipvoip.wjasmit.nl:5060> is not mine! If I use my external IP (188.8.131.52), I see the same error. 3CX is running on Windows Server 2008 R2, which has as hostname: voip.wjasmit.nl, DNS is also working good, the server is behind a NAT firewall (port 5060 and RTP one's are opened correctly). Telephones are working good inside the LAN network as long as I'm using the server ip (192.168.5.245), if I use the DNS name voip.wjasmit.nl INSIDE my LAN network, I get the same error as above :S Does anyone know if I am doing something wrong, or have the solution for my problem? Chris.