Global Positioning System
CarCom utilises the Global Positioning System satellites - around 30 of which are positioned in orbit around the earth. The GPS satellites were initially introduced for use by US Department of Defence, but are now utilised by many companies all over the world to provide location based services. The GPS receiver built in to the CarCom system works by passively receiving satellite signals from which it determines location. When the receiver estimates the distance to at least three GPS satellites it can calculate its position. The vehicle can then transmit this location information to the CarCom Assistance Centre where it is displayed on digital maps.

And even if the vehicle goes under cover (for example an underground car park), we will know when the vehicle went in to the building and of course as soon as it reappears.