Phones transmit location data whenever a phone is turned on, irrespective of whether they are being used to make calls or send text messages and emails.
Details of the giant database of location-tracking information, and the sophisticated ways in which the NSA uses the data to establish relationships between people, have been revealed by the Washington Post, which cited documents supplied by whistleblower Edward Snowden and intelligence officials.
The spy agency is said to be tracking the movements of “at least hundreds of millions of devices” in what amounts to a staggeringly powerful surveillance tool. It means the NSA can, through mobile phones, track individuals anywhere they travel – including into private homes – or retrace previously traveled journeys.
The data can also be used to study patterns of behaviour to reveal personal information and relationships between different users.
Civil liberties experts have long said that cell phone location data contains some of the most intrusive information about people in the digital age, leaving a kaleidoscopic footprint of a person’s life. Phones transmit location data whenever a phone is turned on, irrespective of whether they are being used to make calls or send text messages and emails.