Saving a number during Sip Register

I would like to know if it is possible to save a client’s number during a sip register ?
(note - I am using a stasis application as my logic to route all the calls)

Save what number and how?

Hi Jcolp,
i have Node A (Sip client) which registers to my asterisk and then makes a call to node B (outside world) using a sip trunk.
But the problem is, Node A has its own internal number and then when a call is made to node B, node B sees a standard fixed number (eg XXX). So when a Node B calls back node A , i want asterisk to have a proper correlation between internal number and ‘XXX’ called.
That is why i wanted to know is it possible to save a number when node A tries to register.

I don’t believe so, and registration may not even include that number you are referring to.

Use the CALLERID() function, also make sure you have the option sendrpid = yes on your sip.conf file