I am trading someone off of craigslist, my space gray for his gold iPhone 6 plus. They are exactly the same specs only difference is the color. Here are my questions... Do I need to call AT&T and have the serial numbers or IMEI transferred? I don't want the person that I am trading with to be able to report it lost or stolen and be stuck with a useless phone. I know to back up my phone and wipe it clean and take the SIM card. Since my phone has applecare added and the one I am trading for doesn't. Since the phone is under 60 days, I was just going to have Applecare added to it and have Apple refund the unused portion of my current phone. A regular employee can do that, correct? I don't need to make an appointment, do I?