Carrier early upgrade programs may generally be a rip-off, but thanks to the domino effect created by T-Mobile's Jump, every major carrier needs one. CNET reports that Sprint will debut One Up on September 20th, a payment plan that lets customers pay for new smartphone or tablet devices using monthly installments, and then trade in the device each year for a new one. Sprint's new program follows T-Mobile's JumpAT&T's Next, and Verizon's Edge programs – none of which seem to be a very good deal, once you do the math.

The service might actually be an okay deal

So what's the catch this time? According to a leaked promotional screenshot comparing One Up to its competitors, the service might actually be an okay deal, saving you $220 per year versus T-Mobile's Jump thanks in part to the fact that One Up doesn't have an extra monthly fee. Compared to Verizon and AT&T's plans, which don't offer discounts on service, One Up seems like an even better deal. It's like AT&T Next, in that there's no down payment, and like T-Mobile Jump, in that there's a discount on your monthly plan cost.

Basically, One Up charges about half of a phone's retail price to "rent" it for a year before trading in for a new one (Jump lets subscribers upgrade every six months if they want). But will anyone switch to Sprint just to take advantage of the most cost-effective upgrade plan?