I have a phone I bought that has a clean imei number on it but I'm trying to sell it and I keep getting questions on if it's unlocked and to unlock it if it's not. The phone was originally on sprint and I've never sold a phone that wasn't unlocked before. I got a good deal on this iPhone 7. They didn't need it and got it for free. I'm assuming it was free with some trade in program since it's the 32gig. Can I sell this?