: You paid the full monthly installment for both phones initially. After about three billing cycles, AT&T would begin applying a monthly credit (up to $21.67 or $27.09 depending on the plan) to offset the cost of the second device. Total Credit Value

Participating in these deals often involved several strict conditions as noted by Yahoo News and BGR : Has anyone gotten a new free phone from AT&T? - Facebook

The BOGO offer required customers to purchase both phones on an or AT&T Next Every Year installment plan.

: The credits generally totaled , covering the full retail price of a base 32GB

Historically, AT&T's "Buy One, Get One Free" (BOGO) promotions for the Go to product viewer dialog for this item.

: Both devices had to be from the same manufacturer; for example, you could not buy a Samsung Galaxy S7 and get a free Key Requirements & "Catches"