@dieselvw:
Thanks, Hoba, I'll give those things a try. One other thought that might help in diagnosing this: if I use a Cisco router (such as a 2611) everything works perfectly. An idea to explore, if someone here can do it, is what is unique about the Ciscos that makes them so compatible with these VoIP services? There's a lot to dislike about Cisco – the cost, and overall their mean-time-between-failures leaves a lot to be desired. So, what is Cisco doing that pfsense isn't?
Thanks.
Was this ever resolved? I have exactly the same issue with the same VoIP provider. Nuvio does use proxy servers on the connection from my phones to them, but my phone ringing is still sporadic. I have 2 IP phones in my office and I have them set to 192.168.100.50 and .51. I have enabled Advanced Outbound NAT and set up a rule for static port on the WAN interface for 192.168.100.50/31 which should cover me, but that does not seem to be a total cure. I was using a Snapgear router (based on Linux IP Tables) and did not need any special settings for things to work. I do not mean that as a knock, I just think there is maybe something simple that we're missing here.
Anyone have any other thoughts?
Also, related to this, are Advanced Outbound NAT and Enable IPSec Passthrough mutually exclusive since they are on a radio button together?