hi, I have a very basic question. If I buy a iPhone 6s from att website with full price: 1. Do I still need to activate the phone once I get it? Or I just need to incert my old att SIM card in it and turn on the phone? 2. Together with the new phone, do they ship the iPhone 6s together with a new SIM card (in the iPhone?)? I already have a att post paid SIM card, do i have to use the new sim SIM card (together with the new iPhone 6s) from now on? Thanks!