[SR-Users] How to modify INVITE Request Line string

[Jose Figueroa]

Hello everybody,

Today I received a request from a carrier which needs us to send the calls
using a prefix in the INVITE header.

I am reading the documentation for kamailio 4.3.x but I havent found anything
I can use in order to modify the Request Line (INVITE) string. 

I need to change from this:

INVITE sip:123456789 at IP:5060

to this:
INVITE sip:PREFIX123456789 at IP:5060

If you can guide me to the right direction would be more than great.

Thanks
-- 
Jose Figueroa
Senior Software Engineer