Whilst the growth and advances in the mobile telephone infrastructure has brought untold benefits, it has also brought an increased threat of eavesdropping on private and confidential conversations through the use of Global Systems for Mobile Communications (GSM) based listening devices.

These GSM devices work by using mobile telephone technology and networks to tap into and relay live audio from one location to another. Given the global nature of mobile networks, these devices are able to capture conversations taking place in London and relay them to an eavesdropper based as far away as Sydney.

Being small, simple to deploy, requiring very little power and accessible from anywhere in the world, GSM bugs now pose one of the biggest threats to privacy and security.

The Threat from GSM Bugs

Improved mobile technology and microphones mean GSM devices can easily pick up room audio within a 5 metre radius. This makes them an ideal method for capturing boardroom conversations.

New generation GSM bugs have gone a step further and use motion and vibration detection to sense when a room being monitored becomes occupied. Upon sensing occupation a message is sent to the eavesdropper as a signal to start recording the signals now being transmitted by the GSM listening device.

These new listening devices can also have multi-switchable microphone inputs, allowing the eavesdropper to switch between microphones placed in different locations. For example, a device installed above an office false ceiling can capture conversations taking place in up to 4 meeting rooms or offices. Ideal if an eavesdropper wants to follow the thread of a conversation started in one room and continued in supposed confidence in another.

Being either battery or mains powered, GSM audio surveillance devices can be pretty much permanently on, allowing them to capture a wealth of information over long periods of times if left undiscovered.

GSM Bug Detection

The bad news is that GSM surveillance devices are difficult to detect as their signals get easily lost amongst legitimate GSM and mobile communications.

The good news is that counter surveillance technology is developing fast detect and there are a number of good solutions that effectively deal with the threat from GSM bugs.

SearchLight is one such GSM detection and location system being used by counter surveillance professionals. The advantage of systems such as Searchlight are that they can distinguish between legitimate mobile phone signals and those of GSM bugging devices

Once a hostile device has been detected it can be pinpointed to a precise location. It can be jammed or allowed to continue working while investigators source the agents who placed it in situ or feed false information to the hostile agents.

To ensure the continued smooth running of a business and not to raise suspicions, a white list of safe mobile phones can be compiled to avoid legitimate phones being labeled as hostile.