[SR-Users] RTPproxy in bridge mode question

Guys, I'm successfully using a Kamailio + RTPproxy setup in bridge mode with most of my Gateways. My setup includes two different interfaces one with a public IP and teh other with the private IP. Now I'm facing some slight issue. Some providers won't accept my calls (or calls will have some strange behavior) if the Contact header has an IP out of immediate range. I tried to use fix_nated_contact() function but as per my topology, this function will not change the contact header because the IP is already the one on the interface. Example: U 192.168.200.X:5060 -> 192.168.200.Y:5060 INVITE sip:111160911097@192.168.200.Y SIP/2.0. Via: SIP/2.0/UDP 192.168.200.X:5060;branch=z9hG4bK096baacc;rport. From: "Uriel Rozenbaum" <sip:60911100@192.168.200.X>;tag=as32794d5e. To: <sip:111160911097@192.168.200.Y>. Contact: <sip:60911100@*192.168.200.X*>. U 200.A.A.A:5060 -> 200.B.B.B:5060 INVITE sip:898960911097@200.B.B.B SIP/2.0. Record-Route: <sip:200.A.A.A;r2=on;lr=on;ftag=as32794d5e>. Record-Route: <sip:192.168.200.Y;r2=on;lr=on;ftag=as32794d5e>. Via: SIP/2.0/UDP 200.A.A.A;branch=z9hG4bK5222.14fbf4f7.0. Via: SIP/2.0/UDP 192.168.200.X:5060;received=192.168.200.X;branch=z9hG4bK096baacc;rport=5060. From: "Uriel Rozenbaum" <sip:60911100@192.168.200.X>;tag=as32794d5e. To: <sip:111160911097@192.168.200.Y>. Contact: <sip:60911100@*192.168.200.X*>. Is there any way to let know Kamailio the outgoing IP I'll be using and fix the contact accordingly? I can trigger this change after I know the destination IP. Thanks! Uriel