T-Mobile CEO John Legere on Thursday announced a new “Un-carrier” move that’ll likely once again shake up the wireless industry – the end of data plans. As you may have come to expect from wireless carriers at this point, the devil is in the details.

T-Mobile’s new plan, dubbed T-Mobile One, offers customers unlimited high speed data plus unlimited talk and text for $70 per month for the first line, $50 for the second line and $20 per additional line after that for up to eight lines total. You can add additional lines past eight but they’ll cost $30 each.

The plan includes unlimited standard definition video streaming – if you want HD streams (up to 4K quality), it’ll cost you an additional $25 per month, per line. Earlier carrier perks like Simple Global, Mobile Without Borders, Carrier Freedom, Wi-Fi Unleashed, Stock Up and T-Mobile Tuesdays are all included with T-Mobile One.

That sounds like a decent deal at first but it completely undermines its Binge On service which provides unlimited music and video streaming (480p quality) when using select content providers (the list is quite long as this point and includes almost all of the big names).

And let’s be honest with ourselves – streaming music and video are the main culprits contributing to data overages these days. So really, if these things were already free, what’s the attraction here?

Furthermore, tethering will be limited to 2G speeds under T-Mobile One, which at this point is more or less unusable in all but emergency situations. You can add 5GB of high speed tethering but it’ll cost you $15 per bucket.

Also, in the fine print under the “network management” section, you’ll see that T-Mobile reserves the right to “prioritize” traffic among its highest-consuming users (currently those that use more than 26GB of high speed data per month). In other words, if you use more than 26GB in a given month (which is incredibly easy to do if you’re streaming high-resolution video) then you may see your speeds throttled during times of high network use or congestion.

It’s worth noting that existing T-Mobile subscribers will be able to hang on to their current plans and aren’t being forced into the new plan. T-Mobile’s strategy, however, is to eventually phase out all data plans and offer T-Mobile One only.

The new approach isn’t necessarily a bad deal but it’s far less attractive once you unpack the details. As always, do your research and evaluate which carrier and plan is the best for you and your family before making a decision.

T-Mobile One will be available beginning September 6 for postpaid customers. Those with prepaid accounts will get the option sometime in the future, we’re told.

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