I've got a SIP server at a location runnning 3cx.
I wanted to swap it out with one running sipXecs so there were no limitations on lines on a free version.
I have internal calls and I can recieve external calls.
Problem is when I try to dial out, the server sends a SIP invite to my ITSP, but somewhere along the line it is being blocked by a router somewhere on the net which gives the ICMP response Destination Unreachable Communication Administratively Filtered
This router doesn't appear to be anything to do with my ISP or my ITSP. However if I try and use the original server it still works fine, but the new server does this every time.
I've ensured STUN is setup and I've tried manually specifying the WAN IP which made no difference.
Anyone got any ideas as I've never seen that problem before.