Built-in variable for trunk-context

Hi, I've created a HMR rule to change the trunk-context base on prefix on the ruri, the problem is that i've tried to use built-in variables to generate the new trunk-context

 

sip-manipulation
	name                           routing045
	description                    Trunk-Context 045
	split-headers
	join-headers
	header-rule
		name                           modify_iptel045
		header-name                    request-uri
		action                         manipulate
		comparison-type                case-sensitive
		msg-type                       any
		methods                        INVITE
		match-value
		new-value
		element-rule
			name                           modtrunkcontext
			parameter-name                 trunk-context
			type                           uri-user-param
			action                         replace
			match-val-type                 any
			comparison-type                case-sensitive
			match-value
			new-value                      $T_CONTEXT+^045

 

The new value i'm trying to generate is in this format 045Peer

 

The RURI is arriving in this format:

 

INVITE sip:0451111111111;tgrp=420;trunk-context=Peer@....

 

I want to modify in this format: