[OpenSIPS-Users] Cancel ACK routing

[John Quick]

I had something very similar happening on CANCEL ACK handling.
In my case, it was because I had changed the To header. 

The scenario I had was this:
Invites sent to OpenSIPS had a 4-digit prefix which appeared in both the
R-URI and the To header. I wanted to remove the prefix.
It was easy to change the R-URI and strip the prefix off, but attempts to
use uac_replace_to (from the UAC module) ended up with unexpected problems
So I stripped the prefix from the To header using subst function instead.
That is when I noticed CANCEL would no longer be handled properly just like
Rik is describing.
The TM module (t_relay) was tracking changes made to the R-URI but not those
made to the To header.

Hope this helps you to identify the problem. Rik, are you changing the R-URI
or any of the headers (To, From, etc) when the Invite is processed?

John Quick
Smartvox Limited