A woman looks at her mobile phone Photo by WANG ZHAO/AFP/Getty Images As part of an ongoing Freedom of Information Act suit launched by civil liberties group the Electronic Privacy Information Center, the FBI is turning over information on its use of cellphone surveillance technology variously known as “Stingrays,” “Cell Site Simulators,” “IMSI Catchers,” or “Digital Analyzers.” These devices function as portable surveillance transceivers that are designed to trick phones over a targeted area into hopping onto a fake network. The FBI says it uses the tools to track the locations of individual suspects. But the technology is controversial because, by design, it collects data on innocent bystanders’ phones, and it also interferes with cellphone signals in a way that may be prohibited under a section of the federal Communications Act.