T-Mobile is already becoming a major threat in the U.S. mobile industry with its cheap rates, lack of contracts and aggressive marketing. But the company now wants to take a big step beyond its comfort zone and become a bank. T-Mobile launched a program called Mobile Money on Wednesday, which basically acts as a prepaid Visa debit card attached to a T-Mobile account. The financial institution in the background is actually Bancorp, but T-Mobile is acting as the public face of the operation. Customers can add money to their accounts at T-Mobile stores and Safeway locations or link their paychecks to direct deposit. They will be able to manage their accounts and pay bills from a smartphone app or the web. And they’ll be able to use a network of 42,000 ATMs. Mobile Money is going after a big underserved segment of the American populace, known as the un-banked, and it’s not the first to do so.