AT&T is now offering both new and existing customers a buy one, get one free deal on iPhones for a limited time. As usual, there are a few cavets when it comes to getting your "free" phone.
To start, both devices must be purchased on AT&T's Next installment plan, and while the first phone can either be on a new line or an upgrade, the second phone must be on a new line with an AT&T Next 24 plan. You'll also need a qualifying service plan. After a few billing cycles, you'll start to get $650 in bill credit spread out over 30 months, enough to pay for a 16GB iPhone 6s. At sale, you'll only need to pay the tax on your new phones.
This offer is only available for a limited time, so jump on it while you can.