Hi, user_A with STUN calls to user_B behind NAT with no STUN. onreply_route[1] { if (nat_uac_test("1")) fix_nated_contact(); if (isbflagset(6) && status=~"(180)|(183)|2[0-9][0-9]") force_rtp_proxy("l"); } In the initial request bflag(6) is up because "location" of user_B so RtpProxy is used in the INVITE and 200-OK. But in re-INVITE bflag(6) is down and is not applied force_rtp_proxy("l"); in the 200-OK. In fact I debug the SIP trace in the re-INVITE in OpenSer: ---------------------------------------------------------------------- # user_A -> OpenSer INVITE sip:user_B@112.121.235.28:5061 SIP/2.0 c=IN IP4 212.121.235.18 # OpenSer -> user_B INVITE sip:806@212.121.235.18:5061 SIP/2.0 c=IN IP4 80.94.0.110 <---- RtpProxy applied (OK) # user_B -> OpenSer SIP/2.0 200 OK c=IN IP4 192.168.1.106 [*1] *1: Needs RtpProxy but bflag(6) is down so not applied. # OpenSer -> user_A SIP/2.0 200 OK c=IN IP4 192.168.1.106 <-- RtpProxy NO applied ---------------------------------------------------------------------- But I can confirm that the audio works after re-INVITE in both directions!!! ¿? I've debugged with tcpdump, the RTP is send to RtpProxy from user_A, how is possible?? Thanks. -- Iñaki Baz Castillo ibc(a)in.ilimit.es