Remembering when I had a problem with my first pfSense installation, I had some help from a friend who did a quick packet capture. it seems the ITSP, even after being told three times they were, was still not sending signalling to sipXecs on port 5080. It was being sent to 5060. In doing a quick packet capture, Diagnostics>Packet Capture, it was very easy to turn capture on for the WAN port, call the system from the outside and stop the capture. Then download the capture file and open with wireshark on your PC.
Don't have wireshark? Go get it from the wireshark.org download page!
In my case, looking at the capture file showed the signalling still being sent to port 5060. So that explained a lot. While there are a lot of firewall packages I like, a lot of them lack this feature.