e911

The wireless Enhanced 911 (E911) rules seek to improve the effectiveness and reliability of wireless 911 service by providing 911 dispatchers with additional information on wireless 911 calls.

The wireless E911 program is divided into two parts - Phase I and Phase II. Phase I requires carriers, upon appropriate request by a local Public Safety Answering Point (PSAP), to report the telephone number of a wireless 911 caller and the location of the antenna that received the call. Phase II requires wireless carriers to provide far more precise location information, within 50 to 300 meters in most cases.

The deployment of E911 requires the development of new technologies and upgrades to local 911 PSAPs, as well as coordination among public safety agencies, wireless carriers, technology vendors, equipment manufacturers, and local wireline carriers. The FCC established a four-year rollout schedule for Phase II, beginning October 1, 2001 and to be completed by December 31, 2005.

Source: http://www.fcc.gov/911/enhanced/

Enhanced 911 service or E911 service is a North American telephone network feature that automatically associates the physical address with the calling party's telephone number. This is generally done by a form of reverse telephone directory that is supplied by the telephone company. This provides emergency responders with the location of the emergency without the person calling for help having to provide it. Enhanced 911 has been deployed in most metropolitan areas in the United States. In some places (e.g., Minneapolis/St. Paul) it has been used since the early 1980s, though as of the end of 2002 it was not available in every area.

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.

There is special privacy legislation that permits emergency responders to obtain the caller's information. Even though the caller's number may be blocked for caller ID purposes, the caller's details will be provided to the emergency services.

A second phase of Enhanced 911 service is to allow a wireless or mobile telephone to be located geographically using some form of radio triangulation from the cellular radio network or by using a Global Positioning System built into the phone itself. There are also other proposed features that are intended to allow telephone callers from large corporate telephone networks to be located down to the specific office on a particular floor of a building.

In all cases, the location information provided is normally integrated into emergency dispatch center's Computer-Assisted Dispatch or CAD system, to provide the dispatcher with an on screen street map that highlights the caller's position and the nearest available emergency responders.

Source: http://en.wikipedia.org/wiki/E911

Related (kinda): http://www.kcbd.com/Global/story.asp?s=2932403

More...
http://en.wikipedia.org/wiki/Emergency_telephone_number
http://en.wikipedia.org/wiki/9-1-1
http://en.wikipedia.org/wiki/PSAP
http://www.comm-nav.com/e911.htm
http://people.howstuffworks.com/location-tracking2.htm