T-Mobile USA has gone live with a new unlimited data plan that could help it compete with rival Sprint, the only other top-tier provider in the country to offer all-you-can-eat plans.

The plan, first announced in August, differs from T-Mobile's other data plans by not slowing down speeds for customers who consume a capped amount of data, a practice referred to as "throttling". Users signing up for the unlimited T-Mobile Value plan will pay about $70 a month, while those on T-Mobile's Classic plan will pay about $90.

“Since our inception, we’ve always strived to shake up the industry with plans, network capabilities, and innovative products and services for our customers,” Brad Duea, T-Mobile senior vice president of product management, said in a statement. T-Mobile said the launch of its “Unlimited Nationwide 4G Data” plan comes on the 10th anniversary of the debut of its brand in the United States.

In rolling out its unlimited data rates, T-Mobile drew a contrast between itself and competitors AT&T and Verizon Wireless, which long abandoned unlimited service in favor of a tiered model.

T-Mobile's new unlimited rate does come with some fine print. Subscribers on the plan are not allowed to use their smartphone as a mobile hotspot. Tethering is only available on T-Mobile plans that throttle speeds after 5 GB or 10 GB, depending on the monthly rate.

Like T-Mobile, Sprint does not include tethering in its unlimited plans. Customers who use their smartphone's mobile hotspot capability must pay extra. Sprint offers two tethering add-on plans, $20 per month for 2 GB or $50 per month for 6 GB. 

Unlimited plans, while eschewed by AT&T and Verizon Wireless, remain an important differentiator for Sprint. CEO Dan Hesse attributed the plans to Sprint's iPhone sales numbers last quarter, when its activations remained flat while those at AT&T and Verizon Wireless declined. 

"I attribute it to the simplicity of our rate structure in unlimited," he said. 

That simplicity is one of the aims of T-Mobile's new plans. The operator called Verizon's shared data plans "costly, complicated and punitive" in a July blog post, pointing out that the rates raised prices for some customers. 

AT&T has also rolled out shared data plans. The debut of the plans was marked by controversy after AT&T decided to limit FaceTime access over its wireless network to customers who sign up for the new rates, a move that could encourage subscribers to switch to the plans. 

Restricting FaceTime on cellular connections to shared data plan customers quickly drew fire from public interest groups, who said the move could violate the FCC's net neutrality regulations. AT&T denies the claim.