Prepaid to Contract

You can have him contact at&t and swap it over. Your phone does have a 1 year warranty on it as long as it's not physically damaged

Sometimes my phone will restart it's self out of nowhere. And it usually happens when I go to make a phone call. It doesn't happen all the time, maybe two-three a week. Sometimes twice a day. Oh, and one day I went to answer a phone call and I  could not hear or speak to the person on the other side without putting them on speaker phone. It just messed up out of nowhere. For almost a month I've been having to use speaker phone to hear/talk to people on the phone. It also depends does a scuff/scratch on the screen count as physically damaged (happened last week way after my phone started messing up)? I think it does , just double checking.

Getting on a postpaid plan will not get you a better phone. You can use any AT&T compatible phone on the prepaid service, you just have to pay for the phone up front.