Mashable: “Smartphones are intimate companions: We cradle them in our hands, and hold them close to our chests. They greet us each morning, and whisper in our ears at night. We tell them our secrets. Unfortunately, when it comes to keeping those secrets, our phones have mixed allegiances.  On Feb. 23, T-Mobile, which completed its merger with Sprint in April of 2020, announced that it intends to use customers’ “web and device usage data” for third-party advertising. In other words, the mobile provider, which as of the fourth quarter of 2020 had approximately 102 million customers, will share that customer data with a host of unnamed advertisers.  T-Mobile is not the only cellphone provider that shares its customers’ data. AT&T says it may share customers’ demographic details, among other information, with “advertisers, programmers and networks, social media networks, analytics firms, ad networks, and other similar companies.” Verizon, for its part, says it shares “de-identified information” for ad campaigns and various reporting.  While the three major mobile providers all insist that customer information is anonymized and, in some cases, aggregated before sharing, time and time again we’ve seen in practice how hard it is to truly de-identify an individual’s personal data.  What does this look like in practice? In 2017, a journalist and a data scientist presenting at DEF CON demonstrated just how easy it is to de-anonymize supposedly anonymous web-browsing data. Using about 10 URLs or so, the two showed how they were able to link web-browsing histories to real people, including politicians and a Dutch judge.  This should bother you.  Your phone, and consequently your mobile provider, know a lot about you. The places you go, apps you use, and the websites you visit potentially reveal all kinds of private information — e.g. religious beliefs, health conditions, travel plans, income level… Thankfully, there are small steps you can take to stop this data collection and reclaim an ounce of the privacy that, by default, you deserve…”