NEW YORK (TheStreet) -- The nation's No. 4 wireless carrier, T-Mobile USA (TMUS) , is at it again. This morning, the company's outspoken CEO John Legere announced the latest aggressive assault on the industry's standard offerings with the introduction of UnCarrier 8.0 and a new feature it calls "DataStash".

"Think of it as data rollover," Legere explained. T-Mobile believes that "old-school carriers have rigged the game with plans purpose-built to make you pay for more data than you need -- or pay overage penalties. And then they confiscate what you paid for if it's not used within 30 days, bilking customers out of billions of dollars."

T-Mobile's answer is to offer you the ability to "bank" your unused high-speed cellular data minutes that you pay for each month and then use them when you need them. Those unused minutes remain in your account for one year, through 2015. This new offer is limited to subscribers who sign up for at least 3 GB of high-speed data for phones or 1GB for tablets per month.

Starting next month, the company will launch the program by offering customers 10 GB of 4G/LTE DataStash to start them off.

T-Mobile shares were off 0.48%, to $25.13 in late morning trading in New York.

T-Mobile's "UnCarrier" initiative began nearly two years ago and has been giving its rivals fits ever since. The idea was to change old-fashioned service contracts, end overage charges and early termination fees and abolish the subsidizing of handsets. These moves have produced changes from AT&T (T) , Sprint (S) and Verizon (VZ) , including contract-free service plans and big bonuses for switching from other carriers.

Beginning in March 2013, T-Mobile unveiled UnCarrier 1.0, offering unlimited voice calls and text messaging plus 500 MB of high-speed data for a monthly charge of $50. The data limit was doubled this past March.

UnCarrier 2.0 was nicknamed Jump! and allowed subscribers to trade in or upgrade their phones as many as two times a year. In October 2013, UnCarrier 3.0 added free 2.5G international roaming, as well as 200 MB of free data for tablets (especially for the new Apple (AAPL) iPad).

2014 brough the end of early termination fees in UnCarrier 4.0. In April, version 4.5 created a new $40 a month Starter plan, cheaper 4G tablets, and the end to overage charges for all customers.

UnCarrier 5.0 allowed customers to try iPhone 5S handsets for a week. Then 6.0 ended data charges for accessing music sites such as Pandora (P) , Spotify, Rhapsody, iTunes Radio, Slacker, iHeartRadio (IHRT) and others.

UnCarrier 7.0, introduced three months ago, was all about wi-fi connectivity. It provided free text messages and visual voicemail to customers on Gogo-equipped U.S. flights. Subscribers were made eligible to upgrade to a device that supports "Wi-Fi Calling" (a.k.a. voice over IP, or VoIP, calling) and introduced a personal cellspot home router to improve the quality of those wi-fi voice calls made indoors.

The result of all these initiatives has been to force the other major carriers to follow suit or, at least try to keep up with T-Mobile's offers. All have copied T-Mobile's plan to separate the cost of a phone and the monthly service charges.

Verizon, the number one carrier in the U.S., offers monthly plans starting at $50 for 1 GB of data or $65 if you don't use Verizon's Edge phone purchase program. AT&T calls its handset buying plan "Next" and offers similar discounts. Third-place Sprint has a $50 a month unlimited-everything plan for individuals and also promises to slash Verizon and AT&T rate plans in half. Sprint doesn't include T-Mobile in its latest offer.

On Monday, T-Mobile announced that its fastest Wideband LTE service is now live across the greater New York region, including Brooklyn, the Bronx, Manhattan, Queens, Long Island and Northern New Jersey. That brings the total to 120 markets that have received T-Mobile's best 4G coverage. Tall buildings and a large geographical area mean that the New York metropolitan region is usually not among any carrier's first locations to receive wireless network upgrades.

Under theoretically perfect conditions, this latest Wideband LTE data technology offers peak download speeds up to 110 Mbps.

The company says it has also deployed newly acquired 700 MHz spectrum in Cleveland, Colorado Springs, Minneapolis and Washington, D.C., to improve its network reach and in-building coverage.

-- Written by Gary Krakow in New York.

To submit a news tip, send an email to tips@thestreet.com.

Gary Krakow is TheStreet.com's Senior Technology Correspondent.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.

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