[Serusers] RTP proxy/nathelper

[Dinesh]

As use of the RTPproxy consumes bandwidth on the SER/RTPproxy machines
interface we would like to avoid it's use as much as possible.
It appears that nat_uac_test detects our UA that are configed with port
forwarding or DMZ as being behind NAT there by setting flag 6 and
indicating the use of the proxy.  As these do not actually need the use
of the rtpproxy I want to force the use of the rtpproxy only when the
calling party or the called party has a 5 in the 4 digit of the phone
number eg 222522 or 123588
I have a clue on how to achive this when the called party has a 5 in the
4 digit by testing the uri but how would I test for the calling party.

A code snippet would be highly appreciated.

Regards,
Dinesh