T-Mobile just hugely undercut Apple's new iPhone upgrade plan By Kevin Downey

We've been telling you all about Apple's new iPhone 6s and 6s Plus smartphones, including their improved design and ramped-up performance. We also told you about a really cool, new way to buy Apple iPhones. The best part? You can replace them with newer iPhones once a year.

It's called the iPhone Upgrade Program. Starting at $32 a month, you can essentially lease an iPhone like you lease a car. For that fee, you get an unlocked iPhone, so you can shop around for the best carrier deals.

That's a great option. You no longer have to get locked into a carrier contract, so you'll no longer be stuck with an old iPhone long after everyone else has the newer, shinier and better iPhone.

But, just one day after Apple announced its iPhone Upgrade Program, cellphone carrier T-Mobile has debuted its own lease-to-buy program. Monthly, it's less expensive, too.

With its T-Mobile JUMP! On Demand, the carrier is offering the iPhone 6s for $20 a month, for 18 months, and the iPhone 6s Plus for $24 a month, for 18 months. After the 18 months are up, you can pay a fee to keep your iPhone. For example, you pay $164 to keep your iPhone 6s, bringing the total cost for it to $524. That's a nice saving over the 6s' suggested $649 retail price. AT&T and other carriers are also offering discounts.

T-Mobile is taking its offer a step further, though. It's offering the Lifetime Coverage Guarantee to T-Mobile customers who buy the 6s or 6s Plus. If you're unhappy with T-Mobile's coverage the first month, it'll give you your money back. Anytime after that, it'll unlock your iPhone so you can shop around for other carriers.