A location based communications system uses a physical location system (PLS) or relative position system to determine a communication unit's location in two or three dimensions, and is configured for radiotelephonic calls through intermediary communications satellite systems, cellular systems or other mobile systems and land line systems, based on the location G# of the called telephone or on a caller-defined estimated area or space termed a G zone number GZ# surrounding the desired callee. The system is particularly advantageous for mobile communications, and may be interfaced with conventional stationary telephones, cellular phones and other communications devices. Multiple telephone units may be simultaneously contacted with messages in user-defined languages. Emergency features enable the location based communication system to locate and notify the nearest and/or best equipped party for assistance in the event of an emergency, issue warnings to all phones in a specific area of any size, calculate vehicle velocities and control traffic.