Asymmetric RTP ports

Does Asterisk support asymmetric RTP ports ?
If does, how are we going to enable it ?
I’m running 1.6.2 Asterisk with freepbx
Thanks in advance.

The only Google hit for “asymmetric RTP ports” is this thread. Please explain what you mean.

asymmetric rtp ports = source & destination using a different rtp port for voice .

That’s the normal case for SIP. The recipient chooses the RTP port on which it is going to receive and sends that, in an SDP payload, to the other party. If you set the allowed RTP port range at the two ends so as not to overlap, it will always be the case.

But we had tried open port 1024 ~ 65535, the one way audio problem still exist.
We confirm it is not about NAT problem, we also have similar problem with other ip pbx unit, but different unit having different solving solution, like by disabled “source address filtering” , enable “KeepRTPAddress” etc. Any similiar setting in asterisk ?