A while back T-Mobile announced that it's going to start selling its customer data to third party advertisers. Well, not so much "announced" as "snuck into a modified terms of service and told people they'd have to manually opt out if they didn't like it." It's not very cash money of the "un-carrier," as it's... well, all about the money.
T-Mobile says that the data it passes on to third part will be anonymized, or at least, unconnected to names, account numbers, and other specific data. But combined with the smorgasbord of information available from other sources, it won't be very difficult for advertisers to build up a fairly unique profile of information on individual users.
This data collection is de rigueur for the industry—pretty much every large technology company does it to one degree or another. T-Mobile is at least giving its customers a way to opt out. Here's how you do it.
What To Do
First, log in to your T-Mobile account from a web browser. This should technically be possible on mobile, but if you have a desktop or laptop, it will make the following step a lot easier.
Next, go to this page on T-Mobile's website. It's not easy to find from the main site, so use the link to get right there. Scroll down the page a bit to the section labelled "Do Not Sell my personal information."
Toggle this switch on, with the round ball on the right. Then click the "Done" button beneath.
This should apply the opt out condition to your personal account, and any phones connected to it.
What About Other T-Mo Carriers?
Do a Double-Check
We've managed to go through this process without issue. However, several Android Police readers have told us that the page for this service isn't particularly stable, and it may crash after you click the "Done" button. To double-check and make sure it's active, reload the page and see that the toggle is still set to the right. If it isn't, log out of your T-Mobile account, log back in, and try again.
Can I Do This Again?
If for some reason you want to opt back into T-Mobile's personal data sharing, simply repeat the process again, turning the toggle the other way. T-Mobile will begin selling personal information to its advertising partners starting on April 26th, 2021. According to its announcement, users should still be able to change this setting after that date, keeping any data collected after they switch from being sold.