Inserting P-Access-Network-Info

I am looking to insert P-Access-Network-Info into the INVITE coming from the phone. I believe this is working, however I am wondering in there is a better way to do this or if I am missing something. The regex for matching the IP address from the Call-ID field seems to work, however I'm wondering if there is a cleaner way. 

 

This is what I have so far:

 

sip-manipulation

        name                           Add_PANI

        description                    Add the P-Access-Network-Info Header

        split-headers

        join-headers

        header-rule

                name                           Store_PhoneIP

                header-name                    Call-ID

                action                         store

                comparison-type                pattern-rule

                msg-type                       any

                methods                        INVITE

                match-value                    ((([0-9]{1,3}\.){3})([0-9]{1,3}))

                new-value

        header-rule

                name                           rule_Add_PANI