I have a friend who has a broken iPhone and she’s looking to replace it. She’s been looking on offerup and found a 6 Plus she’s interested in. She asked me a couple of things and while I’m pretty sure I’m right, I’m not 100% sure. So, my question is, my friends current provider is Verizon. The phone she found on offerup is from sprint and it is not unlocked. Will she have an issue activating her SIM on the new phone? If she buys it, can she unlock it herself or does the person selling it have to unlock it first? Any help is appreciated.