T-Mobile USA, a subsidiary of Deutsche Telekom AG (PINK:DTEGY) and the nation’s fourth-largest wireless company, is trying to get an edge over telecom giants AT&T (NYSE:T) and Verizon (NYSE:VZ) with a simple strategy: bring back the unlimited data.

Starting in September, the company will join Sprint Nextel (NYSE:S) and MetroPCS (NYSE:PCS) in offering such a plan, after originally ending its last year.

AT&T and Verizon, on the other hand, each no longer offer unlimited data. Verizon, for one, switched to its  “Share Everything” plan, which makes it easier for customers to hook multiple devices to the network.

T-Mobile had been calling all its data plans “unlimited,” but actually slows down speeds significantly once users hit a certain level of usage each month. The company says that offering unlimited full-speed data again is simply a response to what customers want.

It also seems to be an attempt for the smaller providers to compete with the two biggest names, though. MetroPCS announced yesterday, for example, that it is even cutting the price of its unlimited plan.

The only limitation on the T-Mobile’s unlimited plan is that users cannot turn their phones into mobile hotspots like they could with other plan options. Another turnoff is that MetroPCS and T-Mobile don’t offer the Apple (NASDAQ:AAPL) iPhone, so both may struggle when the highly-anticipated iPhone 5 comes out next month.

Still, re-offering unlimited data may be just what T. Mobile needs to get back on track. The company has seen lots of trouble lately, as it cut jobs, had to pay a whistleblower fine and lost its CEO.