I want to switch from Verizon to ATT, it's my understanding is that all iPhones 6 and newer are unlocked from Verizon. My wife has a 6 Plus and I have a 6s. Is it truly possible to switch from Verizon to ATT and keep our devices? I know I have to buy out my current phones from Verizon. But I don't want to do a buyout then have to buy another iPhone from ATT.