T-Mobile is the smallest of the four nationwide carriers and the only one that doesn't sell the iPhone. But the revamp means that iPhone users could migrate over from Sprint Nextel Corp. and Verizon Wireless when their contracts expire.
Owners of AT&T Inc. iPhones could move over too, if they figure out how to "unlock" their phones from AT&T's network.
AT&T does "unlock" other brands of smartphones on request, and they, too, will work on T-Mobile's revamped network.
Currently, T-Mobile undercuts the other carriers with a contract-free plan with unlimited calling for $70 per month. It includes 5 gigabytes of data, after which speeds are throttled.
