I got a quick question. I currently have service with ATT and do not have any data plan. I do currently own a smartphone but had the phone early enough before ATT starts to require any data plan. Now, I am thinking of buying a iPhone 4 or 3GS (not from ATT or Apple) to use with my current plan. Can I do it? would I still need to sign up for any data plan? Do I still need to activate my phone? Would my 3G phone SIM from my smartphone works with 3GS without any issue? I konw iPhone 4 uses MicroSIM card, can I go to ATT store and would they exchange my SIM to microSIM without any issue and requirement for any additional data plan or service?