What Is it?

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A cell-site simulator (CSS), also commonly referred to as an “IMSI catcher” or “Stingray”, is a device that law enforcement uses to try to locate a suspect’s cell phone. CSSs masquerade as legitimate cell phone towers, thereby “tricking” all nearby cell phones into connecting to the device instead of to legitimate cell towers. CSSs are not restricted in their search to just suspect targets, but log the International Mobile Security Identity (IMSI) numbers of all mobile phones within range of the device; although law enforcement usually claims that their CSSs are configured to only find a specific IMSI and discard any other IMSIs that connect. CSSs are useful to law enforcement because they can pinpoint a phone’s location in real time with much greater precision than cell site location information (CSLI) stored and tracked by cell phone companies.

Key Terms

Content: the substance of the digital communication, such as the body of an email or a text message. Also referred to as digital media, digital content is stored on digital or analog storage in specific formats.

CSLI: Cell Site Location Information is a record of the location of the cell towers that a cell phone connected to at specific moments in time.

IMSI: International Mobile Subscriber Identity is a unique identifying number assigned to each cellular service subscriber. Every SIM card has a unique IMSI number that, when captured, can reveal some identifying information about the registered mobile subscriber.

Metadata: data that describes or relates to another piece of data. An example of metadata might include a message’s sender, recipient, date, time, subject heading, and the IP address from which the message was sent. Other examples include records of when a device or service was in use or idle, and location data indicating where devices have been or, indirectly, whose devices they might have been nearby.

Stingray: A once-popular model of cell-site simulator manufactured by Harris Corp. This term is often improperly used to refer to cell site simulators generally, even though it technically belongs to a specific model of CSS. This kind of over-inclusive brand recognition is much like how the term “Kleenex” is often used to refer generally to a piece of tissue, regardless of the actual tissue brand.

 WITT: The acronym for the FBI’s “Wireless Intercept Tracking Team” tasked with deployment and use of CSSs.