[Serusers] Arbitrarily altering the "Contact:" field

I've got a situation where i need to replicate registrations to an outside proxy, a simple replicate wont work because i need the registration on the outside proxy to reference the SER proxy and not the client directly. The one requirement is that i know (in a scripting context) what the username of the registration is so i can construct a Contact that contains it. The only function i've found that could do this is the subst(///) function in the textops.so module, however its acting very strangely. Ex. subst('/^Contact:.*sip:([0-9]+)@.*$/Contact: <sip:\1@!OUTSIDE_PROXY!>/'); Seems to match properly, but inspecting the packet as its routed out (using ngrep) shows the following contact field "<sip:200010001000@!OUTSIDE_PROXY!>sip:200010001000@!ORIGINAL_IP!:5070." My understanding is that "sip:200010001000@!ORIGINAL_IP!:5070" should have been replaced with <sip:200010001000@!OUTSIDE_PROXY!> instead of being prepended. Perhaps there is a module that provides a function that would allow me to manipulate the contact more easily (i'm aware that the regex in the subst in inadequate and would not match the full range of RFC3261 valid Contact strings, i'm just testing right now) Would anyone be able to offer any advice? tavis