Yesterday, we reported about T-Mobile offering a similar offer: Trade in any iPhone 6 or newer, and you'll receive $650 via statement credits over the course of 24 months for any new line activation or eligible upgrade. Sprint is offering a very similar deal. Actually, it's about the exact same deal, except you can also trade in Samsung Galaxy smartphones to be eligible to get the deal. If you trade in any iPhone 6, 6 Plus, 6S, or 6S Plus, Samsung Galaxy S7, or S7 edge, you'll be eligible to receive $27.09/ month toward your bill for 24 months. ($650 total, the price of a 32GB iPhone...
Source: http://www.gsmarena.com/sprint_follows_behind_tmobile_offering_free_iphone_7_with_tradein_at_t_too-news-20420.php