[Kamailio-Users] phones on two different ports no audio via rtpproxy

I have been using openser/kamailio for some time now and have two ports 5060 and 5090 (both udp) in the configuration or .cfg file. I do use rtpproxy (and have used mediaproxy)for NAT traversal. What I have noticed is that a phone which uses the standard SIP port 5060 (UDP) and calls a phone using 5090 (UDP), the call goes thru using "loose route" and audio also is passed both ways. But when a call from a phone using port 5090 (UDP) is made to a phone which is using port 5060 (UDP), the call goes thru using "loose route" and the bell also rings but there is no audio. Any suggestions on how to make this audio work in this situation? Thanks in advance... Raju