I wasn't on a JUMP plan previous to this. I was on T-Mobile but had long since paid off my device. You can give them ANY smart phone. It doesn't have to be your current device or even a T-Mobile phone. In my case I traded in an old Lumia 521 Windows phone (which I hadn't used in a few years). It happened to be a T-Mobile device but that wasn't a requirement. It was a slow, old phone and was bottom of the line when I bought it four years ago. There are only 3 requirements: it must be a smart phone, it must power on, and the screen cannot be cracked. You don't even need the charger. I have heard of people buying a $10 no-contract smart phone from Walmart and then turning around and going to T-Mobile to use it as their JOD trade-in. If you resist the urge to constantly upgrade while on JOD (or only upgrade once to the iPhone 6s when it comes out), you can save over $200 off the retail cost of the 6 or 6s at the end of the lease, assuming you choose to purchase the phone at that point.