[Christien]

As far as I understand, any loss in signal is reported via the monitoring equipment, and, if prolonged, is treated as either a malfunctioning unit or a disabled unit - if they believe it's disabled, it can get reported as stolen. Some monitoring systems (depending on the level of sophistication/cost) disable the vehicle (prevent ignition from working, lock doors, etc) if the unit is in any way disconnected, unable to communicate with the satellite/cell tower, loses power, etc.