…There are 331 million cellphone subscriptions—about 20 million more than there are residents—in the United States. Nearly 90 percent of adult Americans carry at least one phone. The phones communicate via a nationwide network of nearly 300,000 cell towers and 600,000 micro sites, which perform the same function as towers. When they are turned on, they ping these nodes once every seven seconds or so, registering their locations, usually within a radius of 150 feet. By 2018 new Federal Communications Commission regulations will require that cellphone location information be even more precise: within 50 feet. Newer cellphones also are equipped with GPS technology, which uses satellites to locate the user more precisely than tower signals can. Cellphone companies retain location data for at least a year. AT&T has information going all the way back to 2008.
Police have not been shy about taking advantage of these data. According to the American Civil Liberties Union (ACLU), U.S. law enforcement agencies made 1.5 million requests for user data from cellphone companies in 2011. And under current interpretations of the law, you will never find out if they were targeting you.
In fact, police no longer even have to go to the trouble of seeking information from your cell carrier. Law enforcement is more and more deploying International Mobile Subscriber Identity locators that masquerade as cell towers and enable government agents to suck down data from thousands of subscribers as they hunt for an individual’s cell signal. This “Stingray” technology can detect and precisely triangulate cellphone signals with an accuracy of up to 6 feet—even inside your house or office where warrants have been traditionally required for a legal police search…. red the rest here -> Your Cellphone Is Spying on You – Reason.com.