How to Stop AT&T From Sharing Your Private Data with Advertisers

AT&T wants to share subscriber data with advertisers to make a little extra money.

The company changed its privacy policy to allow it to do so, and in a blog post about the changes promises to protect user privacy. They’ll only sell anonymous, aggregated data, it says:

This is data that can’t be tracked back to you individually. Here’s an easy example: After an election in your community, officials will release the final vote tally. They might say that 60 percent of the voters picked Candidate A and 40 percent picked Candidate B. That information is a type of aggregate and anonymous data. It’s “aggregate” because it combines information for the whole community telling you who the community as a whole voted for, and it is anonymous because the data doesn’t tell you who voted for which candidate.

In exchange, advertisers will know even more about the things you like. “You benefit by having better products available and seeing advertising more relevant to your particular consumer segment,” AT&T says. For example, it says, people who live in an area where marketers have decided people like movies will be more likely to get ads about movie theaters.

Wow, more relevant ads and AT&T making money from our data that it promises can’t be tracked. This sure sounds like a win-win!

If that didn’t blow up your sarcasm detector, let’s talk about how researchers have repeatedly shown that anonymous data really aren’t.

Just a few anonymous pieces of information are enough to identify a specific person in many cases. Ars Technica has highlighted many examples, including how a researcher was able to identify the “anonymous” medical records of Massachusetts’ then-governor with his birth date and ZIP code, how another pair could pick out specific Netflix users by looking at Internet Movie Database recommendations, and how others were able to identify AOL users through their search history.

In each case, the people who released the records took steps to ensure they were anonymous, Ars says — but they failed, because truly anonymous data aren’t very useful or valuable.

AT&T has at least publicized its intent and offered a way to opt out of this data-gathering activity. Go to their website and say no. You’ll have to log in with your phone number and password, and check the box next to each number listed for the account, then click submit.