T-Mobile has found a new way to track customers. Here’s how to stop it.

Smartphone OS providers Google and Android are providing ways for users to opt-out of tracking. Therefore, marketers have been looking at other options to track online activity and T-Mobile has come up with a new way of tracking customers to collect data.

As reported by AdExchanger, T-Mobile’s Un-carrier has a new program called App Insights. The program has been in beta for a year and is now fully launched. It allows third-party marketers to buy T-Mobile’s customer data.

The data is “anonymized” and grouped based on similar behaviors and interests, meaning marketers cannot buy the app history of a specific user. T-Mobile is promoting it with the phrase “Apps speak louder than words,” and telling potential customers to “leverage app insights, the strongest indicator of consumer intent.”