T-Mobile is offering customers loaner iPhones to test its upgraded LTE network

At T-Mobile’s(s tmus) Uncarrier 5.0 event Wednesday night, CEO John Legere trotted out a new concept in the mobile industry: the test phone. Starting Monday, T-Mobile will send any potential customer an iPhone 5s(s aapl) and let him or her have free reign over its network for seven days.

While many operators offer a trial period for your mobile service or device, it’s often more trouble than its worth, requiring you to re-provision to a new phone or carrier and often pay a restocking fee. With T-Mobile’s Test Drive program, you don’t switch carriers, sign a contract or buy device. T-Mobile sends what amounts to a loaner phone for you to try out while you’re still with your current carrier. After seven days you drop the loaner handset off at a T-Mobile store, and you’re then free to remain with your current carrier or sign up for new service with T-Mobile.

Source: Kevin Fitchard / Gigaom
Source: Kevin Fitchard / Gigaom

T-Mobile says it’s a no-strings-attached trial. In an interview, T-Mo’s chief strategy officer Mike Sievert put it a different way: it’s the opportunity to take a “seven-night stand” with T-Mobile, to gauge if your relationship with AT&T(s t), Verizon(s vz) or Sprint(s s) is really worth preserving. If for some reason you like them better, they’ll never have to know about your secret rendezvous with T-Mobile.

Apple(s aapl) is working closely with T-Mobile providing thousands of free iPhones for the trials, T-Mobile said.

It’s an interesting concept and one geared toward focusing consumers on a lot of the big upgrades T-Mobile has been making to its networks. On Wednesday, T-Mobile CTO Neville Ray revealed the carrier has piled a lot more spectrum onto its LTE network, increasing capacity and data speeds by 50 percent in 16 cities: Atlanta, GA; Birmingham, AL; Columbus, OH; Dallas, TX; Detroit, MI; Houston, TX; Jacksonville, FL; Los Angeles, CA; Minneapolis, MN; Mobile, AL; Orlando, FL; Portland, OR; Seattle, WA; Tampa, FL; and parts of upstate New York.

T-Mobile has also expanded its voice over LTE coverage from its initial two cities to cover 15 total, including New York City and San Francisco.