https://www.theverge.com/2017/9/13/16303954/att-sprint-iphone-8-deals-announced-bogo-trade-in

AT&T and Sprint are the first two carriers to announce discounts on the iPhone 8. They’re two pretty different deals, and they both have their perks and limitations.

First up is AT&T, which has a buy one, get one offer on the 8 and 8 Plus. There are a couple catches here: the first, and biggest, is that you have to be a DirecTV or U-Verse customer to qualify. If you are (or you decide to sign up for TV service), then you’ll be able to get a second iPhone at no additional cost, but only so long as you buy the phones through AT&T’s leasing program and maintain service for both of them, essentially locking you in to the carrier for two years.