hello all, already read through lots of posts and the upgrade guide with no answer to my question. i am eligible for upgrade on my account, so i am getting the iphone 4. i currently have the iphone 3g. i was planning on giving the 3g to my dad, who is on a SEPARATE at&t account. he currently has the original iphone. thus, to get my phone going, all i have to do is plug it in and the upgrade happens. QUESTION: how do i go about "transferring" my old 3g phone to my dad's account? will he have to sign a new contract? new sim card? can he choose a new data plan or does everything with his account remain the same (as far as data plan goes)? we will be selling the original iphone (1g) but i'm pretty sure that the sim card for the iphone 1g is different than the sim card for the 3g? thanks in advance for your responses.