[Serusers] Anyone doing something to handle RFC3326?

[SIP]

We've been looking recently at RFC 3326 (Reason header fields for SIP) 
primarily to help with logging in some of our UAs. While I know that SER 
can essentially tack on any header anywhere, I'm wondering if anyone's 
come up with a solution for handling something like the Call Completed 
Elsewhere reason tag:

Reason: SIP ;cause=200 ;text="Call completed elsewhere"


Essentially, this would be sent in a CANCEL message to all clients that 
did NOT pick up the SIP call. Since SER forks off a separate INVITE to 
any contact in the location table matching the intended recipient, it 
would be nice to fire off a reason for a cancel to some UAs which would 
then know not to bother logging a call as 'missed' in the case of 
another phone picking it up.

I'm sure there's a way to hack this using the current functionality (or 
if not, a slight modification of current functionality), but if anyone's 
done it and has a code snippet, that would make life easier.


N.