T-Mobile’s advertising business is offering a new way for marketers to pry into your app-using habits. Ad Exchanger reports that the un-carrier’s new program is called App Insights, and it’s now fully operational after spending a year in beta. The program allows third-party marketers to buy T-Mobile customer data and centers around a key piece of information that it has unique access to: what apps you use.

Customer data is anonymized, and it’s pooled together with others of similar interests and behaviors, so companies can’t buy a specific user’s app history. Still, it’s creepy. The company’s advertising segment touts this offering loud and clear on its website, with the phrase “Apps speak louder than words” splashed across the top of the page. It also invites prospective clients to “leverage app insights, the strongest indicator of consumer intent.” That’s gross. Thankfully, you can opt out.

Image: T-Mobile Advertising Solutions

T-Mobile offers an Android and iOS app called “Magenta Marketing Platform Choices” that allows you to see which companies have your data and opt out entirely. You can also use App Choices if you don’t want to, you know, download a T-Mobile app to opt out of T-Mobile app tracking. According to Ad Exchanger, iOS users are excluded from the program even if they’ve opted in to app tracking.

This kind of creepy behavior from carriers isn’t new, and it’s not likely to get better. With companies like Google and Apple allowing people to opt out of tracking more easily, marketers are looking for different ways to peek into your online habits. Wireless carriers have eagerly jumped in to provide that information, and T-Mobile is only the latest to do so.