T-Mobile was the first of the three national wireless carriers to introduce a pay-for-early-upgrade program when it unveiled JUMP earlier this month. We questioned the worth of JUMP because of its $10 monthly fee and T-Mobile’s requirement that customers make hefty down-payments on their phones. But with the carrier ditching down-payments, at least temporarily, does that change the math?

BY THE NUMBERS
Say you’re thinking of switching to T-Mobile and getting a Samsung Galaxy S4. T-Mobile currently charges a $149 down-payment followed by 20 monthly payments of $24. With the $10/month fee for the JUMP program, a customer who signed up today will have paid out $329 over the course of the first six months — the earliest point at which a JUMP program member can upgrade to a new phone. That’s 53% of the device’s full sticker price of $629.

Starting tomorrow — but only for a vague limited time, see below — T-Mobile is getting rid of down-payments on all smartphones. Of course, it’s raising the monthly rates for each device to account for the upfront cash. So the Galaxy S4 will have a $0 down-payment but will now cost a subscriber $25/month. Again figuring in $10/month for JUMP membership, the total after six months is only $210, or around 1/3 the full retail cost of the phone.

That means JUMP members can upgrade to new phones after only six months, but will only have paid around $50-75 more than what most carriers would charge for a subsidized phone that requires the subscriber to stick around for the full two-year contract before upgrading.

After 12 months, a person who paid the $149 down-payment on the S4 and $30/month in combined phone and JUMP payments will have forked over $509, or 81% of the full device price. The no-money-down subscriber will have paid $420 (67% of sticker price).

Competing upgrade programs from AT&T and Verizon don’t require down-payments, but do have stipulations that make it so program members are paying for at least half the device’s full retail price before being allowed to upgrade. T-Mobile will obviously take a bit of a hit from customers who go the no-money-down route and upgrade after six months, but it also requires that JUMP members turn in their existing device when they cash in an upgrade, so the company is likely recouping some of the money by reselling these devices on the refurbished market.

THE CATCH
One reason we still can’t express more enthusiasm about the combination of no-money-down and JUMP is that we have no idea how long the no-money-down thing will last. T-Mobile says it’s a limited-time offer, but doesn’t put a clock on the deal.

So it’s more than likely that people who go for the no-money-down/JUMP combo will be faced with a down-payment when it comes time to upgrade after six months. This appears to be an attempt by T-Mobile to attract new customers and then lock them into longer terms after they upgrade, which could be a smart move on the company’s part.

BOTTOM LINE
For customers who think the next big phone is only a few months away, this offer could be a chance for one-time savings, allowing them to upgrade in less than a year. When the subscriber cashes in his upgrade, he’ll probably have to make a down-payment on the new device, but he can also ditch JUMP and live with his phone for a couple years while avoiding the $10/month fee.

But we can’t stress enough that JUMP is not a good deal unless you specifically intend on upgrading your device, as membership in the program will cost you at least $60 (six months of $10 fees) and as much as $240 is you never get around to cashing in that upgrade.

Some have pointed out that the JUMP fees include insurance on the device, which normally adds on around $7/month to a phone bill. Given the problems we’ve read about over the years with insurance claims on wireless devices, we can’t really say that this should be considered much of a plus.

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