T-Mobile will begin sharing your web browsing and mobile app data with advertisers starting April 26, 2021. T-Mobile is automatically enabling this for nearly everyone, but you can opt-out to prevent T-Mobile from selling this data to marketers.

This also applies to other T-Mobile-owned carriers, including Sprint and Metro by T-Mobile.

What Data Will T-Mobile Sell to Advertisers?

As The Wall Street Journal reports, a T-Mobile privacy policy update says that the company will begin sharing web browsing and mobile app usage data with advertisers. By tracking your mobile app usage and web browsing, T-Mobile can put you into a group known as an "audience segment." Here's how T-Mobile explains it:

"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."

For example, if you browse a lot of cooking websites on your T-Mobile cellular connection, T-Mobile can put you in an audience segment that's interested in cooking. These "may be used by T-Mobile or sold to third parties to make ads more relevant to you." In other words, you might see a lot of cooking-related advertisements in this scenario.

In exchange, you get more highly targeted ads. A T-Mobile spokesperson told The Washington Post that many subscribers say that they prefer more relevant ads, so that's why T-Mobile is enabling this feature for almost everyone by default. T-Mobile isn't enabling it for children or business accounts, but every other account will have it enabled by default.

If you don't want T-Mobile sharing your data to give you targeted ads, you can stop T-Mobile from doing it.

As Ars Technica points out, The Wall Street Journal argues that T-Mobile is being more aggressive than AT&T and Verizon in selling this data---but AT&T and Verizon still have advertising programs that use your data, too.

How to Stop T-Mobile from Selling Your Data

You can opt-out from T-Mobile's website or in the T-Mobile app. To do so, head to My T-Mobile and sign in with your T-Mobile account, or you can open the T-Mobile app and sign in.

Click the "My  Account" button at the top-right corner of the page and click "Profile."

Click "Privacy and Notifications" on the Profile page.

Click the "Advertising & Analytics" link.

Click your name in the list to change the settings for your phone line.

If you have multiple lines, you will need to repeat this process for each.

Disable the slider to the right of "Use my data to make ads more relevant to me." This will prevent T-Mobile from sharing your data with advertisers.

You may also want to turn off "Use my data for analytics and reporting." This will prevent T-Mobile from incorporating your data into marketing reports.

If you have multiple lines with T-Mobile, click the "Back" button and select another line. You'll have to disable the data-sharing setting for each one.

How to Stop Sprint or Metro from Selling Your Data

If you have Sprint or Metro by T-Mobile, you can change the same setting on your account website. However, the interface looks a little different.

For Sprint, sign in to the Sprint account website. Head to My Account > Preferences > Manage advertising and analytics preferences. Click the line that you want to change the setting for and disable "Use my data to make ads more relevant to me."

For Metro by T-Mobile, use the MyMetro app or access the Advertising & Analytics Data Choices page. You must access this page on your Metro device. If you're using the app, head to Account > Network and Location Settings and disable "Use my data to make ads more relevant to me."