As with all of T-Mobile's promotions, they are made available "for a limited time" which means the carrier doesn't know when the promotion will end until whenever the carrier decides to end it. The Samsung Galaxy Note8 BOGO promotion has been going on since the first day of September. Customers can get a free 2017 Samsung Galaxy S8, S8+, or Note8 smartphone via rebate on a prepaid master card for new or existing customers on a T-Mobile ONE plan who add at least one line. To be eligible for the offer, you must buy any of the aforementioned Galaxy devices on an EIP (equipment installment...
Source: https://www.gsmarena.com/tmobiles_bogo_galaxy_offer_ends_tomorrow-news-27756.php