I am having audio problem with phones behind another NAT (I have my Asterisk PBX inside a NAT and my phones inside another NAT).
Searching the internet, I found that this is known issue due to udp port forwarding between NATs.
I also found that we can solve this problem by using a middle man like Kamailio (OpenSER).
But I could not find how to configure asterisk with Kamailio for NAT traversal only.
Appreciate any help on this.