hi I have configured kamailio and freeswitch on two Ubuntu servers as follows. Sip_TRUNK------> kamailio-------> freeswitch i wan to manage rtp through the kamailio server, first i want to know, 1. can i do it without RTP Proxy ? anyway i tried it with RTP Proxy as follows, I installed rtpproxy on kamailio server and start it using “rtpproxy –F -l pu.bl.ic.ip -s udp:localhost :7722 -u root” it was working Then I put modparam("rtpproxy", "rtpproxy_sock", "udp:localhost:7722") modparam("rtpproxy", "rtpproxy_retr", 2) modparam("rtpproxy", "ice_candidate_priority_avp", "$avp(ice_priority)") mhomed=0 route[FROM_TRUNK] force_send_socket("pu.bl.ic.ip "); rtpproxy_manage("","pu.bl.ic.ip "); $du="sip:ip.of.free.switch:5080"; route(RELAY); then call is received to user and disconnected on freeswitch console get some errors [ERR] switch_core_media.c:7179 AUDIO RTP REPORTS ERROR: [Remote Address Error!] [ERR] mod_sofia.c:2290 CODEC NEGOTIATION ERROR. SDP: v=0 o=- 3679035755 3679035755 IN IP4 pu.bl.ic.ippu.bl.ic.ip s=pjmedia b=AS:84 t=0 0 a=X-nat:0 m=audio 4167841678 RTP/AVP 123 8 0 101 c=IN IP4 pu.bl.ic.ippu.bl.ic.ip b=TIAS:64000 a=rtpmap:123 opus/48000/2 a=fmtp:123 maxplaybackrate=16000;sprop-maxcapturerate=16000;maxaveragebitrate=16000;useinbandfec=1 a=rtpmap:8 PCMA/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 a=rtcp:4167941679 a=nortpproxy:yes a=nortpproxy:yes please advice me thank you