"The buy-one-get-one-free promotion starts Friday and applies to the iPhone 8 and 8 Plus, among other phones. AT&T hasn't said whether the deal will be extended to Apple Inc.'s most expensive phone ever -- the $999 iPhone X, aka 10 -- which marks a decade since the company entered the phone business."
Details are pretty slim (hence being posted in DT) but likely will require 2 year agreement and/ or new activation.
Update: "After vowing to avoid a repeat of the blistering iPhone price war of last year, AT&T Inc. will fire the first shot -- offering a free iPhone with the purchase of another, for customers who also subscribe to its DirecTV satellite service
." + sign up for a new line.