Guys, I am trying to get the 3CX PBX to work with my local VOIP provider here in Ireland. The provider is Blueface (http://www.blueface.ie) and I currently have a working phone system with a single SIP account. I have got this working with a Linksys SPA942 phone from my LAN direct and it works fine. I can run the X-Lite softphone fine and I've got a Seimens IP450S Gigaset setup at home working fine. I'm behind a NAT firewall in each case and I have opened ports 9000-9005 to my 3CX server. When I configure 3CX I get ""ClientRegs:nFailure [CM113006] Registration of sip:firstname.lastname@example.org has failed; reason=Service Unavailable" As far as I can tell all of my settings are correct, I'm not sure why this is failing. Any ideas? The provider has a lot of Asterisk clients and experience but no 3CX yet and I'd really like to use and be able to resell a Windows based PBX.