Powering a Sim card holder

I have this small gadget that I want to build that relies on gsm network. To begin with I have a sim card holder,a gsm sim card and a battery with some wires if course.

I want to get a gsm shield later but first things first.

If I power the sim card holder with the sim on it,does the sim number become callable?

Does the gsm number become callable once I power it?

No, its a secure cryptographic protocol, the GSM module has to talk live to the SIM
to prove to the bsae station its identity - without that you can only make emergency calls.

The SIM-holder is simply a piece of plastic with pins embedded. Putting power to it will do nothing.

The SIM-card on it's own can do absolutely nothing. It's no more than an encrypted device containing a set of keys and an integral processor.