Yes, you can't control much of headers in the CANCEL, but here is about propagating Reason header from incoming CANCEL to the outgoing one. If you remove it from incoming one and then do msg_apply_changes() before tm gets the chance to look at CANCEL, then there is nothing found to propagate.

I added a note to the docs of t_set_no_e2e_cancel_reason() about its usage for INVITE. I will look when I get a chance to see if it can be expanded to work when used for CANCEL.

For now I will close this issue.

—
Reply to this email directly or view it on GitHub.