since a month i try to solve my rtp problem. I´m quite new to OpenSips but i want it to be running on my Server.

Both Phones (phonerLite) are connected and each one could call the other one, the only Problem is - no voice!
Could someone please give me a hint, on using the right module (and parameter) to solve the problem. The Screenshot shows my topology. Both Clients use a public stun Server. I tried to use the rtpproxy but this piece of code use 99% of my CPU - there must be a different way. 

Thanks for any help.