I ordered my iPhone through apple, and it arrived and I'm loving it! On the other hand my mom ordered the iPhone through att, and hasn't opened it yet and is wondering if she can give the phone to my sister who is also under our family plan with att. Is this possible without calling att? I remember with my iPhone when I was activating I entered in my number, last 4 digits of ss, and billing zip code. Can my sister just do this with her number as well? (obviously my mother and sister do not share the same number) If, however, att preactivates the iphone under my mom's number (which is posted outside of the box) then she will just keep it and we'll order another for my sister. Please let me know what options are available, thanks!