FreePBX behind PFSense 4100

Had to upgrade from my old firewall (USG Pro 4 - was randomly freezing, requiring a hard power disco to resurrect). FreePBX has been running perfect for nearly 3 years (outside of self inflicted issues). Rolled the 4100 in place, everything appeared to be fine.

-Except- I neglected to test outbound calling. I did test inbound, it worked flawlessly (as ever), and figured outbound must be working fine also (I’ll take my licks for not following through completely). Anyhow, outbound calls connect to the provider (ClearlyIP, using their module in the FreePBX), calls are properly routed, and destination rings and picks up, just no audio. As long as the receiving party doesn’t hang up, the call stays connected, just no audio in or out.

From the 2 weeks I’ve been trying to fix the outbound calling audio (to be clear, inbound call audio in/out is perfect…only outbound call audio in/out is not passing). I’ve succeeded in killing ALL audio on all calls several times, but able to restore at least inbound call audio each time. I’m certain it’s got to be a NAT issue, but I’m at a loss after these 2 weeks.

Anyone have thoughts…have further clarification questions…requests I go exercise more Googlefu?

What I do know…I’m fairly certain the issue is with the passing of RTP traffic on the 10000:20000 ports. (edit for RTP ports…had typed RDP).

Sounds like it’s not registering to keep the outbound states active and listening for calls. Have you tried this?
https://docs.netgate.com/pfsense/en/latest/recipes/nat-voip-phones.html

Yes, I’ve seen that (it’s one of the many book marks I’ve set up for reference while trying to get this figured out.

Update this evening: I was able to get one outbound call to work, including audio. In my outbound NAT rule, I removed the port range alias for the source. I also changed the NAT mode from Hybrid to Manual. This allowed one single call to work on the outbound, but no more. tried the three other phones, and it was back to what it was doing. Subsequent outbound calls connect, but no audio.

Inbound calls were unaffected and still work. I did a dynamic view of the UDP connections on the firewall, and it looks like inbound are connecting via IPv6. I have Advanced>Networking set to Prefer IPv4. Wondering if that may be the issue, as the outbound rule is specifically looking for IPv4 addresses, not IPv4.

I known this is not for FreePBX but it may help you - pointing you into the correct setup