For this having issues with Asterisk behind a PFsense NAT
Having battled with trying to get Asterisk (Freepbx) working behind my PFSense NAT I came across this very well explained article from the FreePBX Knowledgebase. After following this to the letter I have a perfectly working Asterisk Server behind my PFSense box and I couldn't be happier. Remember though that while this article doesn't explain the Natting requirements you do need to NAT 5060 and 10000-20000 in PFsense and you need to enable manual outbound NAT and Static Port Translation. All these topics have been explained an uncountable amount of times on these forums.
Hope this helps someone out there.
I don't do any NATs and I have an Asterisk PBX running behind pfsense just fine.
The only thing I had to do was:
1. Register with DuckDNS for a dynamic DNS setup.
2. Configure pfsense to keep DusckDNS updated on what my public IP address is
3. Configure Asterisk so that it knows its outbound trunk connection is being natted, and that the public IP address can be found by looking up xxxx.duckdns.org