When a new phone comes out and you're just salivating over how to get it quickly, one of the biggest holdups in the process is often how much you can sell your old phone for and how long that's going to take. This is especially true if you buy your phones off contract, where the price of a new device is often over $500. For a long time now Sprint has tried to ease the pain of both of these problems by offering a trade-in program that lets you bring your old phone in and get some money back, with a guarantee that you can get up to $300 for the device. If you've purchased this device on a contract, as you normally would on Sprint, then this deal might be pretty sweet, often coming in at very close to the price of a new phone on contract so long as your phone isn't too old and is still in good condition.
But what about off-contract phones? T-Mobile has recently started up that guarantees the same buy-back price as Sprint, except that T-Mobile is promising $50 above and beyond what Sprint offers if they happen to say your device is worth more money than T-Mobile stated it's worth. While this is an excellent practice there's some downsides to T-Mobile's trade-in program versus Sprint's. Right now T-Mobile only allows one device per line to be traded in, and it can only be done when you are buying a new phone through Magenta. Sprint's limitation is 3 devices, and can be done at any time, but will assuredly net you less money in the process. Of course with on-contract prices the way they are for phones, the actual device will cost you much less on Sprint up front, whereas with T-Mobile the up-front price is much higher but the cheaper plans make up for that after some time.