Cell phone blockers are being used in Diplomatic convoys as a standard protection feature.  The blockers are employed to prevent the risk of remotely detonated devices.  These devices are usually planted days before the convoy arrives whilst the operator of the device watches from a distance or even from the television.  Once the convoy reaches the target area the operator detonates the device with a phone call to a cell phone that has been rigged to trigger the bomb.  This is the fear that motivates the use of cell phone blocker technology.

Cell phone blocker technology works by saturating the signal range of cell phones.  This means that the blocker is constantly broadcasting noise on the range that handsets use to talk to towers.  Once a cell phone is brought into blocking range of the jammer it can no longer communicate with the cell tower it relies on to function.  Any phones brought into range of the jammer will display no signal.