INTRODUCTION IN THE UNITED STATES….

The idea of a three-digit emergency number in the United States was the result of the urging of some concerned citizens and the Presidential Commission on Law Enforcement in 1967. It was introduced to Congress and committees were formed to decide how to make the concept a reality.

First, the telephone companies had to find a three-digit number that was not being used anywhere in the United States or Canada as a central office exchange or an area code. Other considerations were that it should be easy to find on the telephone dial or easily dialed in the dark. The telephone industry decided on the digits “9-1-1″.

The first 9-1-1 call was placed on February 16, 1968 in Haleyville, Alabama.

At first, ‘Basic 9-1-1′ could only provide a voice connection to a predetermined emergency response agency. Callers knew that a call to 9-1-1 would connect them to the right people for emergency help, but the emergency responders did not have any information other than that provided by the caller. Still, Basic 9-1-1 was a big improvement in emergency services.

Later ‘Enhanced 9-1-1′ provided the caller’s location information and telephone number via special computers and display screens. Enhanced 9-1-1 also provides features for selective routing and selective transfer of 9-1-1 calls to multiple emergency response jurisdictions.

Selective routing is really the essence of Enhanced 9-1-1. A Master Street Address Guide (MSAG) is developed, which lists street number ranges within an Emergency Service Zone (ESZ). The appropriate Police/Sheriff, Fire and Emergency Medical Service for each ESZ is identified and a unique Emergency Service Number (ESN) assigned. All 9-1-1 calls within that geographic area are sent to a pre-defined Public Safety Answering Point (PSAP) responsible for handling calls in that area.