[SR-Users] SDP_NAT on Retry

Hello everybody, we have got a problem with sdp-nat on retries of a 200 OK packet. Due to slow response of our trunk the 200 ok is resend (up to 3 times) but sdp-nat is only done on the first two packets. We are running Kamailio 4.1.0 with the following setup: Trunk --> NAT --> Kamailio --> Voip Bridge The rtp stream from the trunk (public ip) is supposed to go to one of our media gateways (behind 1:1 nat). We use sdp_mangle_ip to replace the private IPs of our Mediagateway with the public ones. This goes well with the first 200 OK packet but not with a retry. A.A.A.A (public trunk media IP) B.B.B.B (our public media IP - 1:1 natted to I.I.I.I) INVITE Trunk --> Kamailio Connection Information (c): IN IP4 A.A.A.A INVITE Kamailio --> Voip Bridge Connection Information (c): IN IP4 A.A.A.A 200 OK Kamailio <-- Voip Bridge Connection Information (c): IN IP4 I.I.I.I 200 OK Trunk <-- Kamailio Connection Information (c): IN IP4 B.B.B.B 200 OK Kamailio <-- Voip Bridge Connection Information (c): IN IP4 I.I.I.I 200 OK Trunk <-- Kamailio Connection Information (c): IN IP4 I.I.I.I ACK Trunk --> Kamailio --> Voip Bridge Our configuration used is the following: route[RELAY] { xlog("L_INFO"," In route Block RELAY \n"); # enable additional event routes for forwarded requests if (is_method("INVITE|SUBSCRIBE|UPDATE")) { if(!t_is_set("onreply_route")) t_on_reply("MANAGE_REPLY"); } if (!t_relay()) { xlog("L_NOTICE", " (ROUTE_RELAY) Relay failed, sending error \n"); sl_reply_error(); } exit; } onreply_route[MANAGE_REPLY] { xlog("L_INFO"," In route Block MANAGE_REPLY \n"); if ( isflagset(20) ) { -- we have to do nat route(SDP_NAT); force_send_socket(KAMAILIO_TO_TRUNK_IP); } else { force_send_socket(KAMAILIO_TO_BRIDGE_IP); } } How can we handle the 200 OK retry? Is there a way to do this? Kind regards Timo Klecker