### Description fix_nated_contact() and removing and appending a contact will malform the SIP packet. I read somewhere that all of the *_hf functions are applied only when the packet is sent out again. Perhaps things are working as intended and I am just asking too much of these functions. #### Reproduction In my onreply_route for 200 OK with SDP: fix_nated_contact(); #dlg_setflag(1); # I want the contact in the dialog table to be the fixed one #Then I want to replace that contact with a contact to Kamailio's public IP and route it to Asterisk #for ACK response. This contact must be here for Asterisk to relay this back to me. remove_hf("Contact"); append_hf("Contact: <sip:$sel(cfg_get.global.publicIP):5060>\r\n"); # insert_hf same problem ### Troubleshooting This results in two contacts, but does not malform. remove_hf after the nat_fix_contact is the issue. fix_nated_contact(); insert_hf("Contact: <sip:$sel(cfg_get.global.publicIP):5060>\r\n"); #### SIP Traffic The inbound 200 OK CSeq: 9865 INVITE Contact: <sip:424242143@devicePrivateIP:5060> Content-Type: application/sdp After fix_nated_contact(); remove_hf("Contact"); append_hf("Contact: <sip:serverIP:5060>\r\n"); CSeq: 9865 INVITE sip:424242143@devicePublicIP:1026Content-Type: application/sdp ### Possible Solutions I managed to get the functionality I wanted with either of these, but they result in two contact headers. I have also noticed that a remove->append->remove->append ignores the remove between appends. Workaround 1 remove_hf("Contact"); insert_hf("Contact: <sip:$tU@$si:$sp>\r\n"); dlg_setflag(1); insert_hf("Contact: <sip:$sel(cfg_get.global.publicIP):5060>\r\n"); Workaround 2 fix_nated_contact(); dlg_setflag(1); insert_hf("Contact: <sip:$sel(cfg_get.global.publicIP):5060>\r\n"); ### Additional Information * **Kamailio Version**: kamailio 4.4.5 (x86_64/linux) f98162 * **Operating System**: Linux 3.10.0-514.2.2.el7.x86_64 # 1 SMP Tue Dec 6 23:06:41 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/issues/977