Carriers were literally giving them away for any iPhone 6s or higher in working condition On trade in. I plan on keeping my phone three years and I am paying nothing for it but the tax I spent when I picked it up. Same thing happened with the iPhone 7. Insane carrier incentives that make the phone virtually free and suddenly Apple has a gangbusters quarter. It isn’t impressive when the phone is literally being given away.
That would be iPhone 8 or higher. With 6s, credit is only $350. To me, that's not worth getting tied down for 30 months.