Ars Technica reports that T-Mobile will start selling customer Web-browsing and device-usage data to advertisers next month. If you use Sprint, that also applies to you since T-Mobile acquired Sprint last year. T-Mobile’s data-sharing program is reportedly more aggressive than AT&T’s or Verizon’s. T-Mobile claims that it doesn’t hand over your name, only a unique identifier, but security researchers have shown how easy it is for advertisers to link such identifiers back to individuals. Visit T-Mobile’s Privacy Notice for instructions to opt out of data-sharing. If you feel the desire to share your opinion of this sleazy program with T-Mobile, we’re sure the company would appreciate the feedback.