A system for increasing the safety of using cellular telephones stores the geographic coordinates of intersections and other traffic features of a local area in a server. The server is interfaced to the cellular telephone network. A programmable GPS enabled telephone handset determines its location upon start-up and transmits that location to through the cellular network to the server. The server responds by transmitting the coordinates of intersections and traffic features surrounding the present location of the telephone handset. As the handset changes location, it determines its new location and compares it to the coordinates provided by the server. If the telephone handset is within a moving vehicle (as determined by the rate of motion of the handset), an audible alarm is issued when the handset comes within a set distance of one of the intersections or traffic features. In this manner a driver speaking on the telephone is alerted before driving into an intersection or other significant traffic feature.