T-Mobile customers who don’t use all of their allotted data in a given month soon will be able to use that leftover data over the course of their next billing cycle, in a new plan unveiled by CEO John Legere on Tuesday. The plan, dubbed "Data Stash," is the equivalent of "rollover minutes" for data, and promises to further up the ante in the price warfare between U.S. wireless carriers.

T-Mobile also is offering 10GB of free storage as a promotional incentive for Data Stash, which begins in January.

The plan was the centerpiece of T-Mobile’s Uncarrier 8.0 marketing event Tuesday, a stunt held four times a year that often features the foul-mouthed Legere using choice language to attack competitors. That aggression – in which T-Mobile has also eliminated contracts and dropped international roaming rates – seems to be paying off for Legere, as T-Mobile was the only mobile company to add customers (2.3 million, in fact) in the third quarter of 2014.

“Americans have been gamed by the carriers into buying huge data plans – all to avoid getting screwed with overage penalties,” Legere said in a press release. “Only to find out they bought more than they need, which is then confiscated by the carrier. For the consumer it’s lose, lose.”

But not all customers are rejoicing. With expectations inflated for T-Mobile’s Uncarrier event, many customers took to social media to say that they already have unlimited data, thus rendering Data Stash irrelevant.





T-Mobile also announced this week that it has expanded its wideband LTE service, which offers a “theoretical” peak download speed of 110 Mbps. It’s now available across the New York metropolitan region, including areas of Long Island and New Jersey.