San Francisco, June 25 : US telecommunications giant T-Mobile is allegedly selling user information to marketers. However, customers have the option to check which companies have access to their data and can opt-out entirely. T-Mobile's new programme is called App Insights, and it is now fully operational after spending a year in beta, citing Ad Exchanger, The Verge reported The programme 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 anonymised, and it is pooled together with others of similar interests and behaviours, so companies cannot buy a specific user's app history, the report said. The company's advertising segment touts this offering 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". However, users can opt-out of the programme. T-Mobile offers an Android and iOS app called "Magenta Marketing Platform Choices" that allows users to see which companies have their data and opt-out entirely. Users can also use App Choices if they do not want to download a T-Mobile app to opt-out of T-Mobile app tracking. According to Ad Exchanger, iOS users are excluded from the programme even if they have opted into app tracking. /IANS