Why would you? The math doesn't work out at all.
I assume you're on a subsidized plan. You buy an iPhone for $200 or $300 + taxes. After 2 years, you can sell the iPhones for $300 - $500 (depending on storage options), and you come out ahead $100 - $200 in your pocket.
With the lease, even at $5, you pay out of pocket $120 - $240 over 2 years, with nothing to show for it.
Why would anyone go this route???