Enhanced 911

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Enhanced 911, E-911 or E911 is a North American telecommunications based system that automatically associates a physical address with the calling party's telephone number, and routes the call to the most appropriate Public Safety Answering Point (PSAP) for that address. The caller's address and information is displayed to the calltaker immediately upon call arrival. This provides emergency responders with the location of the emergency without the person calling for help having to provide it. This is often useful in times of fires, break-ins, kidnapping, and other events where communicating one's location is difficult or impossible.

The system only works in North America if the emergency telephone number 911 is called. Calls made to other telephone numbers, even though they may be listed as an emergency telephone number, may not permit this feature to function correctly. Outside Canada and the United States this type of facility is often called caller location, though its implementation is dependent on how the telephone network processes emergency calls.

Contents

History

The first 911 system was installed in Haleyville, Alabama, in February 1968 as a way to quickly connect a subscriber to the local police station. This system did not identify the caller but did provide a means to access emergency services that had not previously been available. This system was quickly adapted and improved by other telephone companies to become the E911 system which provides both caller location and identification. A pioneering system was in place in Chicago by the mid-1970s, providing both police and fire departments access to the source location of emergency calls. Enhanced 911 is currently deployed in most metropolitan areas in the United States and Canada.

Public safety answering point (PSAP)

The final destination of an E911 call (where the 911 operator sits) is a Public Safety Answering Point (PSAP). There may be multiple PSAPs within the same exchange or one PSAP may cover multiple exchanges. The territories (Emergency Service Zone) covered by a single PSAP is based on the dispatch and response arrangements for the fire, police, and medical services for a particular area. Most PSAPs have a regional Emergency Service Number (ESN), a number identifying the PSAP.

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