Is there a better way to test your mobile network than to give out free iPhones for seven days with no strings attached? I don’t think so. At T-Mobile’s Uncarrier 5.0 event Wednesday night, CEO John Legere shared a new concept in the mobile industry: the test phone. Starting Monday, T-Mobile will send any potential customer an iPhone 5s and let him or her have free reign over its network for seven days. T-Mobile has been making a lot of network upgrades and 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. It will be interesting to see how consumers respond to this test and how T-Mobile’s network handles the traffic.