[Serusers] sdp rewrite problem

Hello there, I am working on SER with two network interfaces. EP1--------------->(172.16.16.160) SER (192.168.5.1) -------------> EP2 what happens, SER receives invite from EP1, it reinitiates invite for EP2. now what it does is that it writes the external IP i.e. 172.16.16.160 in the SDP contact info, where as it should be the internal one i.e. 192.168.5.1 ... now I want to overwrite the SDP contact info in that invite. I have got two options to do it one option is to use force_rtp_proxy("ei", "192.168.5.1") or use sdp_mangle_ip() function of mangler.so . but they are not working for me. when I play around with force_rtp_proxy function rtpproxy get crashed and sdp_mangle_ip() is not behaving properly ...... whats your experience ? I have used ser-0.8.14 and now using ser-0.9.0 with cvs rtpproxy. I am running rtpproxy like rtpproxy -s udp:192.168.5.1 -l 172.16.16.160 and I am using this line in ser.cfg modparam("nathelper", "rtpproxy_sock", "udp:192.168.5.1") I am really stucked please help !!!! thanking you regards, -- Atif