I'm trading in my iPhone 6 128GB Silver to Amazon. It was activated on AT&T for a year, but AT&T just unlocked it since it's out of contract now. My question is, which of the two models below do I have to trade-in? The two listed on Amazon are: - Apple iPhone 6 128GB (4.7-inch) 4G LTE Factory Unlocked GSM Dual-Core Smartphone - Silver ($537.27) - Apple iPhone 6 128GB 4G LTE Unlocked GSM Cell Phone - Silver ($430.04) As far as I can tell, these are exactly the same. Why then the discrepancy in price and which am I supposed to choose? Anybody else trade their iPhone in on Amazon and successfully chosen? Thanks.