Over the weekend, T-Mobile posted a new slate of rates for what it still calls “unlimited” (though that term is highly debatable) data plans for smartphones, with the lowest tier starting at only $50/month.

That plan allows for 500 MB of data, after which speeds are throttled until the next month starts. Alternatively, customers can get additional 2 GB/month of 4G data in $10 increments. So 2.5 GB will cost $60, 4.5 GB is $70, all the way up to 12.5 GB for $110. All the details are now available on the TMO website.

There is also an actual unlimited plan that will run you $70/month, which is less expensive than comparable plans on the three other major carriers.

Of course, that money needs to be made up somewhere, which is why T-Mobile has decided to stop subsidizing smartphone costs. But rather than require customers to pay the full price for new phones, which generally cost hundreds of dollars, up front, T-Mobile is offering installment plans for devices.

For example, the Samsung Galaxy S II can either be purchased for the full price of $414 or for a down payment of $29.99 followed by payments $16/month for 24 months. T-Mobile is hoping these installments, when added to the data plans, will still be less expensive than what you’d get from a competitor.

“How consumers will react to T-Mobile’s ‘UNcarrier’ approach is something we should learn in swift order,” writes TmoNews.com’s David Beren, “so long as the company can work toward explaining the value — something they’ve had trouble doing in the past.”

The bigger question regarding T-Mobile’s future is when it will finally launch a 4G LTE network. As that becomes the standard for T-Mobile’s competitors, the company may have a difficult time attracting data-hungry customers, even with the lower rates.

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