GSM Tracker-200 is using Mobile phone tracking technology relies on the use of triangulation - taking the signal strengths registered from the mobile phone at a minimum of three nearby GSM receiver masts. As the mobile phone companies know the position of each mast, and can tell the signal strength of the mobile phone device at each of these nearby masts, they can use this to calcuate your position to a certain degree of accuracy (within about 50 to 100 meters). Revolutionary GSM mobile phone tracking technology now allows registered users to locate mobiles and then display the position instantly on a web map for many countries - with an accuracy of up to 50 metres. Whether you run a fleet of vehicles operating in time and service critical industries or have traveling property,mobile phone location technology is the simple, easy to use, alternative to investing in expensive GPS satellite location systems. If your business is mobile then you need GSM mobile tracking! -Works with any GSM mobile SIM CARD -Very low cost for unit tracking hardware invest -Much Cheaper than GPS/Satellite Tracking Specification: Working GSM frequency:900MHz/1800MHz Working Voltage:12V-30VDC