What would happen if I put my not yet activated Sim Card in my Iphone?

My new plan is going to get activated on dec 25/13 but I just really want to start using my new iphone, and I can't use it until I insert a sim card.so, what would happen if I put the sim card in it that is not yet activated?

Just try setting up the phone without sim in it. See what happens. IPad can be activated like that