What is E911 and How Does it Work?

Everything you need to know about Enhanced 911

Person calling roadside service

Getty Images, 


ViktorCap, Getty Images

9-1-1 is the North American universal telephone number for people to dial for help during an emergency. It's vitally important for the 911 dispatcher to know where to send the police, fire truck or ambulance, so 911 is tied to your physical address when you call from a landline phone. For mobile devices, E911 or Enhanced 911 automatically gives the GPS location of the phone to the dispatcher.

GPS location is especially important in situations where the mobile caller is unable to provide the location. Enhanced 911 is a process that happens automatically when a 911 call is placed from a mobile device and does not require any special effort or code on your part to access the service.

Prank calls to 911 ties up the emergency lines and keeps dispatchers from handling real emergencies. In some areas, prank calls to 911 are illegal. If you accidentally call 911, do not hang up. Explain to the dispatcher that there is no emergency. Otherwise, the dispatcher may have to send a police officer to verify everything is okay.

How 911 Calls Work

When an E911 call is made, it is routed to a Public Safety Answering Point (PSAP), a call center operated by the local government. PSAP dispatchers are able to pull your name and billing address, the physical address, or (in the case of a mobile caller) geographic coordinates of the caller so that they can direct the emergency responders to the correct location.

How E911 Evolved

The Public Safety and Homeland Security Bureau, under the Federal Trade Commission (FTC) is in charge of improving public safety through our national, seamless communication systems for emergencies, including 911. As communication technology continues to evolve, our 911 system needs necessary, periodic upgrades to match these advancements in technology. Ensuring these modifications are made is a law, put in place in 1999, with the Wireless Communications and Public Safety Act, known as the 911 Act.

For example, when the first 911 call was placed in 1968, there were no cell phones. All phones were tied to a physical address, which 911 dispatchers could access, by law, from telephone company records.

Prior to E911, when a 911 call was placed with a mobile phone, 911 would go through their mobile service providers to get verification of 911 service before the call was routed to a PSAP. The FCC then required that all 911 calls must go directly to a PSAP without receiving verification, and must be handled by any available phone service carrier, even if the mobile phone is not part of the carrier's network.

Getting More Specific Location Through E911

As another step in improving 911 service, the FTC mandated that all cellular telephone carriers provide more accuracy to PSAP in locating a caller's location. The first part of the phase was enacted in 1998, requiring that all mobile carriers identify the originating call's phone number and the location of the signal tower, accurate to within a mile.

In 2001, the second phase of the program required that mobile carriers provide a 911 caller’s latitude/longitude (X/Y) of the phone's location. This location data is accessed through the GPS chip on the mobile phone. The GPS location can only be activated during a 911 call. The process for identification is called Automatic Number Identification (ANI), and Automatic Location Identification (ALI).

These E911 rules apply to all wireless licensees, broadband Personal Communications Service (PCS) licensees, and certain Specialized Mobile Radio (SMR) licensees.

Limitations to E911

While the X/Y coordinates can help dispatchers find your approximate location, there are limitations. These quadrants are not helpful if the call is coming from a multi-story building. The Federal Communications Commission (FCC) is now requesting that carriers provide a vertical location, a Z-axis location to more accurately pinpoint where a caller located.

911 is the number to call for emergencies in North America. If you are traveling, you will use a different code, such as 112 if you are in England or 065 in Mexico. If you will be visiting another country, memorize the emergency contact numbers for the countries you will be visiting.

E911 may not be enough to help 911 dispatchers find your location quickly in an emergency. The FCC accuracy standards range from within 50 to 300 meters, which could take responders valuable time in finding you during an emergency. For these reasons, whenever possible, try to provide the 911 dispatcher with the following information:

  • Your location or landmarks.
  • Provide the emergency operator with your wireless phone number, so if the call gets disconnected, the emergency operator can call you back.
  • Reserve 911 for emergencies and use the designated non-emergency in your area for needs that are not emergencies.