IncrediblePBX (beefed up FreePBX) is one of our favorite PBX distros. The version 13 by ingenious Ward Mundy is even better than it’s predecessors but it does have some drawbacks.
Regardless of if the installation is done ‘from scratch’ or from the ISO, many users report problems with no audio when iptables is running.
Solution is quite simple:
Edit the iptables file:
nano /etc/sysconfig/iptables
Enter the following line (with most ISO installs it’s already there but it is commented out):
-A INPUT -p udp -m udp --dport 10000:20000 -j ACCEPT
Voila!