Sprint has a BOGO offer for the iPhone 6s and 6s Plus
Here’s how Sprint describes the offer:
Customers can purchase their new phones with monthly installments over 24 months OR lease them with 18 monthly lease payments. They can even mix it up by leasing one and purchasing the other one. Either option will get a monthly offset credit for the second, lower-cost device. Best of all, this offer works with two iPhone 6s, iPhone 6s Plus or one of each.
This BOGO offer works if the customer adds one new line of service and is eligible for an upgrade. In addition, buyers of the iPhone 6s or 6s Plus can also save $200 if they also buy an iPad (iPad Mini 4, iPad Air 2, iPad Pro 9.7, and iPad Pro 12.9) with a lease or monthly installments.
See at Sprint