I bought the original iPhone two years ago. Now I'm traveling in Europe and have decided to sell it here unlocked because it commands a much higher price in Europe. I will keep my SIM card. When I return back to the States one of the first things I'll do is go to my local AT&T store and buy a new 3GS and then simply sync it to my iMac which has all my contacts, apps, music etc. Can I just give them my old SIM card or just my iPhone number and they will activate the new one, or do I need to have my old iPhone present? Will they be suspicious that I didn't bring my old iPhone to the store?