Covert surveillance technology such as IMSI-catchers has long been at the epicentre of debates around privacy against protection. As the world becomes less predictable and the terror landscape evolves, the ability to intercept mobile phones, monitor conversations and track people could significantly improve national security, but at a perceived cost to individual privacy.

An IMSI-catcher works by mimicking a phone base station and fooling nearby mobile phones into connecting to it, giving the authorised person access to the International Mobile Subscriber Identity (IMSI) number. The miniaturisation of technology has meant that, where an IMSI-catcher could only be used in a fixed place in the past, now it can be made portable. This, alongside a wider commercial availability of IMSI-catchers, has created new opportunities for their use. In environments such as prisons, airports, critical infrastructure and government embassies, the intelligence this technology can provide to security services is crucial.

Phones behind bars

In prisons and detention facilities around the world, contraband mobile phones have long been a security and public safety concern. Almost daily, prisoners are using illegal mobile phones to facilitate a wide range of criminal activity from behind bars including drug supply; large-scale fraud; harassment of witnesses; the procurement of firearms; and perhaps most worryingly, maintaining and enhancing the influence of prisoners convicted of terrorism offences.

Nearly 12,000 contraband mobile phones were found in prisons in England and Wales last year. With the current prison population in England and Wales at approximately 80,000 prisoners, that equates to roughly one phone for every six inmates.

To understand the full picture of illicit mobile use in prisons and identify and prevent criminal activity, prison security teams can apply to use IMSI-catchers to gather intelligence on the patterns of behaviour around these illegal communications. This can include how devices and SIM cards move through a prison, monitoring which inmates have control of the device.

Staff then have the insight to undertake in-depth analysis of the communications to support possible ongoing criminal investigations and take positive action by intercepting the calls. Depending on the laws of the land and following ministerial authorisation, prison officers can use IMSI-catcher technology to identify the location of contraband mobile phones, down to the precise cell.

New technologies taking off

Airports could also benefit from the intelligence gathered from IMSI-catchers. Gathering information on a ‘normal’ journey through an airport, such as the average time it takes to move through a terminal or how many communication devices passengers carry on them, helps to build a comprehensive picture around airport activity and identify any possible abnormalities.

Like many other high-risk locations, the use of closed circuit TV (CCTV) has become commonplace in airports to monitor behaviour and identify security threats. But complementing that with a comprehensive overview of social intelligence relies on different layers of technology to collect valuable information in real time.

Consider a staff-only area as an example. If a group of ground staff were gathered in a secure zone (whereby all their IMSI numbers were whitelisted), an IMSI-catcher could immediately detect if any unverified mobile device entered the restricted area, monitor movements and communications and work as part of existing control systems to alert security staff. The purpose of the IMSI-catcher is to add another detailed layer of security to existing measures, such as CCTV cameras, passport control, security screening, airplane manifests, Wi-Fi access, and building access, to enable airport security to respond rapidly to any potential threats and ensure the safety of passengers, employees and visitors.

Privacy vs. protection

There has been an ongoing debate surrounding the ethics of using surveillance technology such as IMSI-catchers, with critics arguing they are an invasion of privacy. While this is an important consideration, it does not trump the duty to protect the public when it comes to national security and the safety of the public at large.

It may be some time before IMSI catchers can shake off their bad reputation, but perhaps now is the time to explore the potential for the technology to significantly improve security measures.