Can you buy an iPhone and just put the sim card from your existing ATT 3G phone in I did so in my brother's iPhone and got service and wanted to know if there was a way to do this with a new iphone?
An AT&T 3G sim card will work in a new iPhone.
yessss you can :) but the box for the iPhone comes with a little tool to help you open the little compartment for the sim card.... its hidden right under that part where the phone is displayed, under that flap thing....... yeah... WELL its silver and has a small tip! not hard to miss! :) okay bye!