Enhanced 9-1-1

E911enhanced 911Wireless Enhanced 911911911 call911 emergency call center911 requirementcaller locationE-911E9-1-1
Enhanced 911, E-911 or E911 is a system used in North America to automatically provide the caller's location to 911 dispatchers.wikipedia
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911911 call9-1-1 call
Enhanced 911, E-911 or E911 is a system used in North America to automatically provide the caller's location to 911 dispatchers.
In approximately 96 percent of the U.S., the enhanced 9-1-1 system automatically pairs caller numbers with a physical address.

Emergency telephone number

emergency callemergency numberemergency calls
911 is the universal emergency telephone number in the region.
Enhanced 911 and similar systems like E112 can provide the location of landline callers by looking up the physical address in a database, and mobile callers through triangulation from towers or GPS on the device.

Assisted GPS

Alltel, Verizon Wireless, T-Mobile 3G, and Sprint PCS use Assisted GPS.
A-GPS is extensively used with GPS-capable cellular phones, as its development was accelerated by the U.S. FCC's 911 requirement to make cell phone location data available to emergency call dispatchers.

Cell site

cell towercell towerscell phone tower
Calls from cellular phones are received via cell towers by mobile switching centers (MSC).
In the United States, for emergency calling service using location data (locally called "Enhanced 911"), it was required that at least 95% of cellular phones in use on 31 December 2005 support such service.

Public safety answering point

public-safety answering pointPSAPintegrated control center
An incoming 911 call is routed to a Public Safety Answering Point (PSAP), a call center operated by the local government.
Most PSAPs are now capable of caller location for landline calls, and many can handle mobile phone locations as well (sometimes referred to as phase II location), where the mobile phone company has a handset location system.

Wireless Communications and Public Safety Act

In the US, the Wireless Communications and Public Safety Act of 1999, also known as the 911 Act, mandated the use of E911 and designated 911 as the universal emergency number, including both wireline and wireless phone devices.
It is also known as the 911 Act. The act required the setup of enhanced 911 and mandated that 911 serve as the emergency number for non-land line phones as well.

Bandwidth (company)

Often, the contracted 3rd party further subcontracts the actual ALI database management to companies such as Intrado, Bandwidth and TeleCommunication Systems, Inc. The ALI database also feeds the Master Street Address Guide database which is used to route the call to the appropriate PSAP and when the call arrives, the ALI database is queried to determine the location of the caller.
Bandwidth offers communications APIs that allow companies to embed voice calling and messaging capability into their applications; enhanced 911 (emergency) calling; and access to virtual phone numbers.

Radio resource location services protocol

Radio Resource Location ProtocolRRLP
Both approaches are described by the Radio resource location services protocol (LCS protocol).
The protocol was developed in order to fulfil the Wireless Enhanced 911 requirements in the United States.

Location-based service

location-basedlocation-based serviceslocation
Mobile phone users may also have a selection to permit location information to be sent to non-emergency phone numbers or data networks, so that it can help people who are simply lost or want other location-based services.
This can be especially useful when dialing an emergency telephone number – such as enhanced 9-1-1 in North America, or 112 in Europe – so that the operator can dispatch emergency services such as emergency medical services, police or firefighters to the correct location.

Location information server

The Location Information Server is a service that is provided by an access network provider to provide location information to users of the network.
The location information server, or LIS is a network node originally defined in the National Emergency Number Association i2 network architecture that addresses the intermediate solution for providing e911 service for users of VoIP telephony.


Cellular networkradio
Cellular networks can determine a more granular location of the caller's device by using triangulation from the cell towers (radiolocation).
This ability is known within the NANP (North America) as wireless enhanced 911.

Global Positioning System

GPSGlobal Positioning System (GPS)global positioning systems
Many phones manufactured after 2005 have GPS receivers built in. When the cellular phone detects that the user is placing an emergency call, it begins to transmit its location to a secure server, from which the PSAP can retrieve it. Cellphone manufactures may program the phone to automatically enable GPS functionality (if disabled) when an emergency call is placed, so that it may transmit its location.
Cellular telephony: clock synchronization enables time transfer, which is critical for synchronizing its spreading codes with other base stations to facilitate inter-cell handoff and support hybrid GPS/cellular position detection for mobile emergency calls and other applications. The first handsets with integrated GPS launched in the late 1990s. The U.S. Federal Communications Commission (FCC) mandated the feature in either the handset or in the towers (for use in triangulation) in 2002 so emergency services could locate 911 callers. Third-party software developers later gained access to GPS APIs from Nextel upon launch, followed by Sprint in 2006, and Verizon soon thereafter.

Mobile phone tracking

location informationlocation historymobile positioning
The Location Information Server is a service that is provided by an access network provider to provide location information to users of the network.
Frequently the compulsion associated with a legislative framework, such as Enhanced 9-1-1, is required before a service provider will deploy a solution.

112 (emergency telephone number)

1121-1-2112 emergency number
In the European Union, a similar system exists known as E112 (where 112 is the emergency access number) and known as eCall when called by a vehicle.
This directive is based on the FCC's Enhanced 911 ruling in 2001.

Plain old telephone service

POTSLocal Telephone Servicetelephone
These circuits are similar to traditional telephone lines, but are formatted to pass the calling party's number (Automatic Number Identification, ANI).
The services include voicemail, Caller ID, call waiting, speed dialing, conference calls (three-way calling), enhanced 911, and Centrex services.

Reverse geocoding

Reverse geocoding
Combined with geocoding and routing services, reverse geocoding is a critical component of mobile location-based services and Enhanced 911 to convert a coordinate obtained by GPS to a readable street address which is easier to understand by the end user.


In the European Union, a similar system exists known as E112 (where 112 is the emergency access number) and known as eCall when called by a vehicle.
Enhanced 911

Voice over IP

VoIPvoice over Internet Protocolvoice-over-IP
As Voice over Internet Protocol (VoIP) technology matured, service providers began to interconnect VoIP with the public telephone network and marketed the VoIP service as a cheap replacement phone service.
Such emergency services are provided by VoIP vendors in the United States by a system called Enhanced 911 (E911), based on the Wireless Communications and Public Safety Act of 1999.

National Emergency Number Association

These solutions are being developed through the cooperation of the Voice on the Network Coalition and the National Emergency Number Association.
NENA is tracking the deployment of Enhanced 9-1-1 and the Wireless Phase 1 and 2 initiatives.

Holdover in synchronization applications

holdoverholdover modeprovide synchronization to wireless base stations
Within the base station, besides standard functions, accurate timing and the means to maintain it through holdover is vitally important for services such as E911

Department of Public Safety

public safetypublic safety departmentMinnesota Department of Public Safety
Emergency communications: operates the public interface emergency communications telephone system by providing the 9-1-1 and Enhanced 911 emergency telephone numbers.


Flowroute's services include SIP trunking, local DIDs and toll-free numbers, outbound termination, and network services such as E911, CNAM Lookup, CNAM Storage, and local number portability.

Mobile phone features

featuresmobile phone contentCameras in mobile phones
GPS receivers integrated or connected (i.e. using Bluetooth) to cell phones, primarily to aid in dispatching emergency responders and road tow truck services. This feature is generally referred to as E911.