Hi !
We have different carriers, some of them send contact in ACK & BYE, some not, but problem persist only when in-Dialog messages have Record-Route header. I can't put here real conversations, but can reproduce signaling in lab.
Here is the signaling & debug log without contact in ACK, with Record-Route header present. [call1.log](https://github.com/kamailio/kamailio/files/7163114/call1.log) [dump1.txt](https://github.com/kamailio/kamailio/files/7163118/dump1.txt)