If you’ve ever filed a public records request with your local police department to learn more about how cell-site simulators are used in your community—chances are good that the FBI knows about it. And the FBI will attempt to “prevent disclosure” of such information.
Not only can these devices, commonly known as "stingrays," be used to determine a phone’s location, but they can also intercept calls and text messages. During the act of locating a phone, stingrays also sweep up information about nearby phones. Last fall, Ars reported on how a handful of cities across America are currently upgrading to new hardware that can target 4G LTE phones.