Mobile Call Logs Can Reveal a Lot to the NSA

Telephone metadata -- including phone numbers, call time and duration, and information about device interactions with cellular towers -- gives intelligence analysts a clear window into sensitive interactions and movements of the U.S. population.

The term “metadata” simply refers to information that is used to track or describe another piece of data, whether that is a cell-phone conversation or a money transfer. One study published this March, using records provided by a European wireless carrier, shows the surveillance power of telecommunications metadata. Vincent Blondel, an applied mathematician at MIT and the Université Catholique de Louvain in Belgium, and collaborators analyzed 15 months of anonymous call records from 1.5 million people. His team was able to uniquely pinpoint the movements of 95 percent of people from only four records, using only the location of a nearby cellular station and the time each call was made. “You can infer a lot, such as where people work and where people live,” says Blondel. “You don’t need information about the content [of the call].”