Sprint is offering a 64GB iPhone 8 for $0 a month if you trade in an iPhone 7 or 7 Plus or one of Samsung’s 2017 flagships – Galaxy S8, S8+ or Note8. Those... are not cheap devices to trade in.
And to be clear the “$0 a month” is after you get $29.17 in credit for the 18 monthly payments for the Sprint Flex lease. You still need to activate a new line, so it's not exactly free.
The 256GB version or the larger iPhone 8 Plus are not part of this promo. However, if you’ve already pre-ordered a 64GB iPhone 8, you haven’t missed out – you can trade in a device to get the deal.
Alternatively you can trade an older device for 50% off the Flex lease for an iPhone 8 (64GB again). The list of eligible devices is longer and basically covers the iPhone 6 and 6s (Plus versions too) as well as 2016 flagships from Samsung, LG, Google and Motorola. Hit the Source link to see the full list.
Verizon also has a trade-in program – you get $300 off iffor an iPhone (from 6s and up) or a Galaxy (S7 and up), a Moto Z2 Force or Pixel XL. Lesser discounts are available for older devices and some not so old (e.g. an HTC 10 gets you $100 off, same as a Galaxy S5... ouch).