[Serusers] non-symmetric rtp with rtpproxy??

Hi, I know this probably is a useless question, as rtpproxy says it is a symmetric proxy ... but i have to ask, for peace of mind :) In my setup, i have on one side a symmetric rtp phone (A) ... connected to a ser proxy + rtpproxy ... and on the other side, a non-symmetric phone (B). This is all on a lan, so no firewalls and stuff ... but I MUST use the rtpproxy and I MUST use this non-symmetric phone (more like a gateway, actually). A ------ SER+rtpproxy ------ B (nonsym) So, the funny thing happens that i end up reciving audio from B to A ... and then I hear A's own audio after being bounced by B (funny, huh?). The bouncing is due to rtpproxy changing the rtp port where he sends to B ... he starts with the one announced on SDP ... then, after the first RTP received from B, he switches to this new port ... mmmm I guess this is a lost cause ... but maybe someone has a brilliant idea?? :D (like a hack in rtpproxy which suddenly turns it into non-symmetrical-rtp-supported-endpoint proxy? :D ) Regards, Cesc