IMSI Locator

IMSI locators, or International Mobile Subscriber Identity locators, are surveillance tools used to intercept and track mobile phone signals by identifying the unique IMSI number of a mobile device. IMSI devices, often referred to as IMSI catchers or stingrays, mimic legitimate cell towers, compelling nearby mobile phones to connect to them. This allows operators to monitor communications, capture metadata, and pinpoint the geographical location of targeted phones. In defense applications they are deployed for intelligence gathering, counterterrorism operations, and securing military communications by detecting and monitoring adversarial movements and activities.
Overview IMSI Locator
By Mike Ball Last updated: July 12th, 2024

IMSI locators and detectors are devices that can be used for cellular and mobile phone surveillance and tracking by military, law enforcement and intelligence agencies.

These types of locator devices are available in a variety of form factors. They may be mounted in a ground vehicle, aircraft or drone, and body-worn and portable devices are also available.

There are two main forms of these devices – passive and active:

Passive IMSI catchers work by intercepting cellular communications and decrypting them to extract information such as a phone’s IMSI (international mobile subscriber identity), IMEI (international mobile equipment identity) or TMSI (temporary mobile subscriber identity) numbers.

Active IMSI locators operate by spoofing legitimate cell towers and providing a stronger signal that causes devices in the vicinity to disconnect from the real network and establish a new connection.

Military Applications for IMSI Locators

Low-SWaP IMSI Locator & Wi-Fi grabber UAV payload by Revector

Low-SWaP IMSI Locator & Wi-Fi grabber UAV payload by Revector

IMSI number trackers are used by military, government and law enforcement personnel as cell phone trackers and target locators. They can be used to provide extremely precise geographical locations of targets without the need to involve network operators, and can typically track multiple devices simultaneously. Location data can be plotted on a map to provide real-time surveillance of targets. In addition to locating suspects and hostile threats, IMSI catchers can also be used for military search and rescue and disaster relief missions.

Active cellphone locators also provide a range of features that may be highly useful for surveillance and tactical operations. They may be able to intercept or spoof voice calls and SMS messages. Connected devices can be forced down to older and less secure communications technologies such as 3G or 2G. Selective jamming attacks may be enacted on target devices in order to provide denial of service, and phone batteries can also be drained.