NAT issue

Hi Guys,

Disclaimer: Yes I know my test platform is weird, with that said,

Here is my setup

Public IP A and B go to pfsense firewall. Fusion PBX box and ASTPP box are behind the firewall on a private network.

Public IP A is nated to the fusion PBX box on all the appropriate ports for SIP and RTP . ASTPP is like wise nated on public IP B. The idea is to use fusion PBX as the PBX and ASTPP as the switch/mediator . A phone from the public network registers to Fusion PBX and Fusion PBX sends all calls to the outside world through the ASTPP box. The Fusion box talks to the ASTPP box on the private newtork

Everything is great, A phone registered to the Fusion box can make and take calls from the outside world except that the calls get disconnected after 31 seconds. Obviously a NAT issue. However internal calls on the Fusion box work fine and if I register a softphone from the public network to the ASTPP box it can take and make calls no problem.

Both boxes have RTP-external and SIP-external set to their respective public IPs

I've tried just about everything I can think of and I really don't want to hang the ASTPP box out on the public network.

Any suggestions would be helpful.
Ok, after much trial and error aka learning the hard way I figured this out.

So basically ASTPP comes with only one profile out of the box. I was trying to do everything through this one profile and as a result the SIP headers would get mucked up one way or another and I'd get an ACK timeout.

The solution was to split this into to 2 profiles one external and one internal (I now see the wisdom in why fusion does this out of the box). both profiles are still behind the firewall but one is responsible for the messy NAT stuff and one is strictly for box to box communication. handing off to the internal profile normalizes the SIP headers and is working so far.

The details are too messy to sum up succinctly in a post so if anyone needs to know feel drop me a line or comment on the post and I'll do my best to explain it.