T-Mobile was the first mobile provider in the U.S. to introduce a contract-free service that allows users to pay off their smartphone in monthly installments and upgrade more than once every two years. The “Jump!” service was billed by the self-styled “un-carrier” as a big shake-up of the U.S. mobile industry. The industry has now quickly followed T-Mobile’s lead, with AT&T and then Verizon both launching similar rapid-upgrade offerings this month.

Today, T-Mobile announced that it is, just weeks after announcing it, improving its Jump! promotion. Customers will now be able to obtain a smartphone -any smartphone – from the carrier for $0 upfront, though they will still have to make monthly payments on the device and sign up for wireless service from T-Mobile. The deal begins on Saturday, July 27.

The originally announced Jump! promotion required subscribers to pay a down payment for each device. AT&T’s “Next” promotion was offering devices without any down payment, and T-Mobile has now matched that.

Included in the deal are top-of-the-line smartphones, such as Samsung’s Galaxy S devices, Apple’s iPhones, and the HTC One. Any smartphone in T-Mobile stores will be available without an upfront payment, though the monthly payments for individual devices do vary. Apple’s iPhone 5 and Samsung’s Galaxy Note II, for example, would require a payment $27 per month, while the Samsung Galaxy S4, HTC One, BlackBerry Q10, and Sony Xperia Z would cost only $25 per month.

“The number of reasons not to switch to T-Mobile this summer is zero,” said John Legere, CEO of T-Mobile. “This is a fantastic offer and we’re making it easier than ever for customers to get the latest amazing devices. Adding zero down in addition to Jump!, and Simple Choice with no contract is all about making wireless work for consumers and shaking up this industry.”

The U.S. wireless market is becoming ever more saturated, and carriers are beginning to compete heavily for every subscriber. As the fourth-largest mobile provider in the U.S., T-Mobile is working harder than most, taking on the larger carriers with new deals, lower prices, and unlimited data plans.