Family plans are all the rage with wireless companies. Get groups of customers to buy a bucket of data together for a discounted price. This morning, T-Mobile announced a new plan that it hopes will lure customers in from AT&T, but the company isn’t making a big deal out a major restriction that could make the offer unattractive to some families.

On its face, the T-Mobile Simple Choice family offering is a good deal — 4 lines for a total of 10GB of data for $100/month. That’s $60/month cheaper than comparable plans from AT&T or Verizon.

But there’s a catch, and it involves how those 10GB are allotted.

See, on the AT&T plan the users in the group get 10GB to share however they wish, meaning broadband-hungry teens can stream music and movies while borderline luddite dad only uses a little bit of data to check e-mail.

But the T-Mobile plan portions out the 10GB into four equal allotments of 2.5GB each. That’s still more than most people use in a month, but it does mean that the family data hog will hit a wall while the family’s data-averse members will not be using the large majority of the data available to them.

Additionally, like the comparable plans from AT&T and Verizon, the T-Mobile plan includes tethering. If there is a student or frequent traveler on this plan who might need to use their wireless device to connect their computer to the Internet, that 2.5GB allotment could be eaten away easily.

In its defense, the T-Mobile plan does not charge overages for users who go over their 2.5GB; it just throttles their data. So you’d get slower data, but you wouldn’t have to pay the ridiculously high overage fees charged by the competition.

So who is the T-Mobile plan right for? I’d venture that a family of four people who are each frequent users of data, but who aren’t gobbling up gigabytes streaming videos over their wireless network (obviously, streaming over your home WiFi doesn’t count). It could be a chance to save some money and may be worth considering.

Of course, T-Mobile isn’t giving people much time to think it over. The plan launches on July 30, but will only be available until Sept. 30. Those who sign up lock in the rate through Jan. 2, 2016.

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