Random One Way Audio on Remote Extension

I have the latest FreePBX Distro installed with 30 extensions hooked into it. All of the local extensions work perfectly, however on the remote extensions they all experience random one way audio drops. I recently put them in a VPN tunnel to see if that would help the issue, but it is the same whether they are in the tunnel or hitting my public IP.

Ports forwarded to the Asterisk server

5060 UDP

10001-20000 UDP

The SIP NAT setting is set to yes and my public IP is on the external IP. I also have my local networks listed. Also this is Asterisk 11 Please let me know if you need anymore information.

Check the /etc/asterisk/rtp.conf file just to double check that you have the correct UDP port range for RTP. I thought it was 10000-20000 rather than 10001-20000.

Normally it is 10000-20000, however I edited it to be 10001-20000 and it shows that in the RTP file.

Did you reload the config?

I have reloaded the server as well as performed a reboot. The ports are forwarded to the PBX server incase you were wondering.

Does the firewall you use have SIP ALG or SIP Helper functions? If so switch them off as they can cause all sorts of such issues.

I use the Untangle firewall which does have the SIP helper function, I have that turned off.

Did disabling the SIP helper seem to fix the issue? I had this same issue with Rempote Polycoms and had to set the RTP Keep alive timer to a lower setting, 20 seconds.

I actually don’t have RTP keep alive on, it is set at 0. What did you set yours too?

20 seconds, I think 30 is normal, but I wanted to be safe, haven’t had an issue since

I added the keepalive to 20 and reloaded asterisk. It screwed up the audio and made it sound like the person was talking through water. Any other ideas?