Just who is providing all the iPhones that will be offered to potential T-Mobile customers as part of a new program that lets people test drive the carrier’s network for a week? Apple. That’s according to T-Mobile CEO John Legere, who said Cupertino is doling out the now nine-month-old handsets free of charge. The test drive program, which was announced today at the company’s”Uncarrier 5.0″ event, lets anyone take home an iPhone 5S that runs on T-Mobile’s network, and comes with the company’s unlimited plan. At the end of the week, people bring the phone back, and either sign up for a plan or return it with what T-Mobile says are no strings attached. Legere said he expects the company to do a million test drives within the first year of the program. That’s a relatively small number of phones for Apple, which sold 43.7 million iPhones in its last quarter. T-Mobile is also not initially offering the service with devices made by other manufacturers, something that clearly benefits Apple this late in the iPhone 5S’s lifecycle.