A cell site simulator (also known as a stingray) emulates a cellphone tower and forces cell phones to register their location and identifying information with the stingray instead of with real cell towers in the area. Stingrays can track cell phones whenever the phones are turned on, not just when they are making or receiving calls. Stingrays force cell phones in range to transmit information back at full signal, consuming the battery faster. When in use, stingrays evaluate all the cell phone handsets in the area, which means that large numbers of innocent bystanders' location and phone information are captured.
"A cell site simulator is a mobile device that captures the signaling information — the phone number, serial number, etc. — of cell phones within the vicinity. The cell site simulator mimics a cell site tower in that it reads signaling information broadcast in public by cell phones turned on in the area. After locating [the suspect] through physical surveillance, agents will position the cell site simulator nearby. Any cell phone that [the suspect] possesses (if turned on), as well as other cell phones nearby, will transmit their signaling information to the cell site simulator. Agents will repeat the process multiple times at different locations and times. By identifying the signaling data common to each capture — i.e., the signaling information that comes up each time, agents can determine the signaling information for a phone used by [the suspect]."