I have this scenario where I have an ongoing transaction.

I receive a 180 (non 100rel) with some to_tag, which i forward back to the caller.

Then I receive an 183 (100rel) which is forwarded back to the caller, who in turn PRACKs it.

It is then that Kamailio (apparently) can't match that transaction internally and replies to the caller (the one PRACKing the 183 (100rel)), with 493 FORBIDDEN.

I'm attaching a trace flow. (Kamailio is 10.255.0.1)

Anyone ever encountered this?

Is this valid and should work?