I'm planning on upgrading to the 4S from a Blackberry Bold (AT&T), but my upgrade eligibility is not until the 4th of November. My sister has an upgrade available and she offered it to me, but we have separate plans. Assuming there is a chance to even buy the 4S in store by the time I am eligible for an upgrade, can I have my sister purchase one with her upgrade and hand it over to me? I know the 4S uses micro sim cards and my Blackberry uses regular sized ones. Could I take the 4S into an AT&T store and have them activate the phone for me and retain my unlimited data plan? Thanks for any advice.