SIP Rule to Insert Data into method CANCEL

I'm a little concerned that you don't have a way to unset the array if the call ends normally. This will potentially fill up your memory. You should look into using the session add/lookup commands instead as these can use a timeout to remove stale data. Basically, you'd want to use:

session add uie $callid [findstr $fullpacket "P-Asserted-Identity:" 0 "\r"]

instead of:

set ::callidtable($callid) [findstr $fullpacket "P-Asserted-Identity:" 0 "
" ]

and then use:

id = [session lookup uie $callid]
if { $id ne "" } { ...

instead of:

if {[info exists ::callidtable($callid)} {...

You could thereafter simply refer to $id and to then also you can use:

session delete uie $callid

in place of the unset.

I am a little puzzled by the -2 stuff since \n is actually only 1 character (a linefeed). Perhaps you really want "\r\n" there.

Hope that helps. It it looking like a pretty cool rule.