Recent news stories, notably this story in USA Today and this story in the Washington Post, have brought to light extensive use of "Stingray" devices and "tower dumps" by federal -- and local -- law enforcement agencies to track cellular telephones.
Just how how does all this tracking and interception technology work? There are actually a surprising number of different ways law enforcement agencies can track and get information about phones, each of which exposes different information in different ways. And it's all steeped in arcane surveillance jargon that's evolved over decades of changes in the law and the technology. So now seems like a good time to summarize what the various phone tapping methods actually are, how they work, and how they differ from one another.
Note that this post is concerned specifically with phone tracking as done by US domestic law enforcement agencies. Intelligence agencies engaged in bulk surveillance, such as the NSA, have different requirements, constraints, and resources, and generally use different techniques. For example, it was recently revealed that NSA has access to international phone "roaming" databases used by phone companies to route calls. The NSA apparently collects vast amounts of telephone "metadata" to discover hidden communications patterns, relationships, and behaviors across the world. But, as interesting and important as that is, it has little to do with the phone tracking techniques used by local law enforcement, and it's not what we're talking about here.
Phone tracking by law enforcement agencies, in contrast to intelligence agencies, is intended to support investigations of specific crimes and to gather evidence for use in prosecutions. And so their interception technology -- and the underlying law -- is supposed to be focused on obtaining information about the communications of particular targets rather than of the population at large...
http://www.crypto.com/blog/celltapping/
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