“When we sell audience segments, we do not sell information that directly identifies customers, like name, address, or email. Rather, audience segments are associated with mobile advertising IDs, which are long set of numbers and letters. For example, this might say something like “2drdn43np2cMapen084″ is a sports enthusiast.”
If you want to keep T-Mobile from selling your data, head over to My T-Mobile and open the “Account” tab. Then, go to “Profile Settings,” open “Privacy and Notifications,” and click “Advertising and Analytics.” You should see the names of everyone on your phone plan. Click one of the names and turn off “use my data to make ads more relevant to me.”
If there are multiple people on your plan, then you need to go back and complete this process for every name in the “Advertising and Analytics” page. If you’re subscribed to Sprint or Metro, follow the opt-out steps at the bottom of our guide on How-To Geek.
T-Mobile isn’t the only carrier to collect and sell customer data, of course. If you want to opt-out of “relevant advertising” on Verizon or AT&T, head to your My Verizon settings or AT&T privacy controls.
Source: T-Mobile via Wall Street Journal