Can't find anything on AT&T's website, but:
AT&T Buy One, Get One Phone Free
Buy one smartphone and get one of the same manufacturer free via bill credits. In order to qualify, one phone must be a new line activation, and both lines must enroll in AT&T Next installment plans. Terms and conditions apply, see a Target Tech rep for details.
Buy one smartphone, get one free when you buy and activate both with an eligible monthly installment plan for AT&T. Offer eligible for new lines of activation and upgrades (if one of the lines is new).