[SR-Users] Is the Contact header required for the dialog module?

Dear List, I’m trying to set up the dialog module and I keep getting the error "bad sip message or missing Contact hdr”: --- Jan 23 11:34:17 server.example.com kamailio[2495]: 16(2511) ERROR: {1 78451036 INVITE 2ef1d082-3486-123d-0abc-02c8e9c6c24e} dialog [dlg_handlers.c:219]: populate_leg_info(): bad sip message or missing Contact hdr Jan 23 11:34:17 server.example.com kamailio[2495]: 16(2511) ERROR: {1 78451036 INVITE 2ef1d082-3486-123d-0abc-02c8e9c6c24e} dialog [dlg_handlers.c:952]: dlg_new_dialog(): could not add further info to the dialog --- This is for MRCP traffic and the SIP INVITEs do not contain the Contact header. They look like this: ---- INVITE sip:some.mrcp.server.example.com:8060 SIP/2.0 Via: SIP/2.0/TCP 10.10.10.10:5099;branch=z9hG4bK5Kpey3r13SBNQ Max-Forwards: 70 From: <sip:10.10.10.10:5099>;tag=134a3eKD2a8Ua To: <sip:some.mrcp.server.example.com:8060> Call-ID: 051df0ff-3541-123d-f090-02f373ff014c CSeq: 78491159 INVITE User-Agent: google_stt Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, PRACK, MESSAGE, SUBSCRIBE, NOTIFY, REFER, UPDATE Supported: timer, 100rel Content-Type: application/sdp Content-Disposition: session Content-Length: 329 v=0 o=FreeSWITCH 2474358185109188492 5282339568667506935 IN IP4 10.10.10.10 s=- c=IN IP4 10.10.10.10 t=0 0 m=application 9 TCP/MRCPv2 1 a=setup:active a=connection:new a=resource:speechrecog a=cmid:1 m=audio 12034 RTP/AVP 0 8 96 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:96 L16/8000 a=sendonly a=mid:1 ---- According to the RFC, the Contact header is not mandatory (https://datatracker.ietf.org/doc/html/rfc3261#section-8.1.1) and I don’t have an easy way of adding the Contact header to the INVITEs. Is there a way to configure Kamailio’s dialog module to do without the Contact header? Any pointers appreciated. Thank you so much With best wishes, Unai Rodriguez