T-Mobile (NASDAQ:TMUS) has undoubtedly made some disruptive moves in the past year. The first big move came when the company did away with contracts. But it's T-Mobile's most recent move that really highlights just how aggressively the company is trying to acquire new customers. The strategy is clearly working. In the company's fourth quarter T-Mobile added about 870,000 new net postpaid customers. But the big gain in customers came with a cost.

As T-Mobile aggressively pursues new customers, it is facing two major challenges: costs and demands for better service. In the following video, Fool contributor Daniel Sparks takes a closer look at these challenges.