In 1996, a Federal Communications Commission (FCC) directive mandated wireless service providers implement E911 or geolocation technology in two phases. Under Phase I, wireless carriers had to provide emergency dispatchers with a wireless caller’s number and location of the nearest cell site. Phase II, due for implementation in the Fall of 2001, requires carriers to identify the location of the caller within 125 meters at least two-thirds of time. There are two categories of wireless E911 location determination technology: handset-based and network-based. Network-based works with two or three cell sites to determine where a caller is located, and handset-based fits a global positioning system (GPS) device to a cell phone. Currently, Phase I is occurring in hundreds of communities but is still behind schedule and Phase II implementation is still early and progressing slowly. Developers of various network-based or handset-based systems are described.