[msboy2011]

i ordered my 3G a couple a days ago when it comesin my dad wants to have my old iPhone. he currently has a blakjack also with AT&T (uliminted Data). can we just put his sim in or is it gonna need an unlock??

[Imahottguy]

Well... He could just pop his SIM in and then you could restore jailbreak/fake activate it. I don't know for sure if activating a used iPhone on your account resigns your 2-year agreement.

Really, that would be the only detriment. Data would be the same, if I'm not mistaken...