SOLVED RTP issue

[bcmike]

Ok, so I've probably made this install more complicated than it needs to be but here is my issue:

Calls set up ok but there's no audio on 75 percent of the calls, so obviously a media issue (RTP)

Now the complicated bit, how the network is setup

The Fusion pbx has its own public IP on a pfsense firewall with SIP (UDP/TCP 5060, 5061) and RTP (UDP 10,000 to 40,000) nat'd to the fusion pbx box on the internal network.

The ASTPP box has its own public IP on a pfsense firewall with SIP (UDP/TCP 5060, 5061) and RTP (UDP 10,000 to 40,000) nat'd to the ATPP pbx box on the internal network. The ASTPP box is registered to a carrier via SIP trunk.

The Fusion PBX box has a gateway setup to the ASTPP box on the internal network.

You with me..

Now the kicker. The phone registers from the public network to the Fusion PBX (reserve judgment for later please) via SIP.

So like I said calls setup ok, but no audio for three quarters of the calls. Also all calls to voice mail or other internal extensions are no problem. I'm guessing all this nating is really screwing with the RTP stream somewhere. At first I thought it might be a port or codec mismatch but I've eliminated that.

My next step is to hang the ASTPP box out on the public network and just lock it down but I'd rather not. Any ideas?

 

[DigitalDaz]

If the fusionpbx and the ASTPP are on the same network then you shouldn't be natting the fusionpbx

 

[bcmike]

The only thing Nating to the Fusion PBX is the phone that registers from the public network. The link between ASTPP and Fusion is on the local subnet.

I'm going to simplify and register a phone to ASTPP on the local network and see if I have the same problems.

 

[bcmike]

Ok, I fixed it and of course it was something stupid.

These are test machines and because of that I'm using the stock iptables rules they both came with during setup. I guess I assumed because they're both Freeswitch projects that the products would've been operating on the same RTP range. Nope...

Iptables RTP rule on the fusion box was 16384 to 32768, and on the ASTPP box it was 14000 to 20000. Now the Freeswitches don't really care as they'll still negotiate RTP between them just fine but of course the local iptables rules need to be adjusted or stuff just works some of the time.

Anyway the solution was to increase the iptables port range on the ASTPP box to 32768 as the lower part was already permissive enough.