Abstract: A vehicle tracking system makes use of a conventional cellular telephone network including a plurality of fixed cellular transmitter sites each covering a predetermined area. The system includes a plurality of cellular signal processing units for installation at hidden locations in vehicles to be monitored. Each unit is connected to one or more different sensors in the vehicle, at least one of the sensors being a break-in detector for detecting tampering with the vehicle, and to a cellular antenna, and includes a controller for monitoring the sensor outputs and initiating an emergency message transmission to a remote monitoring station in the event of actuation of a sensor.