Enhanced 911 or E911 service is a North American telephone network (NANP) feature of the 911 emergency-calling system that automatically associates a physical address with the calling party's telephone number. World map showing North America A satellite composite image of North America. ... The telephone or phone (Greek: tele = far away and phone = voice) is a telecommunications device which is used to transmit and receive sound (most commonly voice and speech) across distance. ... A telecommunications network is a network of telecommunications links arranged so that messages may be passed from one part of the network to another over multiple links. ... The North American Numbering Plan (NANP) is a system for three-digit area codes that direct telephone calls to particular regions on a public switched telephone network (PSTN), where they are further routed by the local network. ... A telephone number is a string of decimal digits that uniquely indicates the network termination point. ...

This is generally done by a form of reverse telephone directory that is supplied by the telephone company as a computerized file. Computer software makes an association between the callers' line and an address. 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 your location is difficult or impossible. Moscow phone book, 1930. ... TATA Engineering and Locomotive Company A telephone company (or telco) provides telecommunications services such as telephony and data communications. ... Emergency services are services that deal with emergencies and other aspects of Public Safety. ... Look up Emergency in Wiktionary, the free dictionary An emergency is a situation that poses an immediate threat to human life or serious damage to property. ... It has been suggested that this article or section be merged with Distress call. ... It has been suggested that Firetending be merged into this article or section. ...

A pioneering system was in place in Chicago by the mid-seventies 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. A metropolitan area is a large population center consisting of a large city and its adjacent zone of influence, or of several neighboring cities or towns and adjoining areas, with one or more large cities serving as its hub or hubs. ...

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. Many countries public telephone networks have a single emergency telephone number, sometimes known as the universal emergency telephone number or occasionally the emergency services number, that allows a caller to contact local emergency services for assistance. ... Most emergency vehicles in the US and Canada display Emergency 911 9-1-1 (nine-one-one) is the emergency telephone number for the North American Numbering Plan (NANP). ... Many countries public telephone networks have a single emergency telephone number, sometimes known as the universal emergency telephone number or occasionally the emergency services number, that allows a caller to contact local emergency services for assistance. ...

Outside 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.

Public Safety Answering Point (PSAP)

The final destination of a 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 covered by a single PSAP is based more on historical and legal police considerations rather than telecommunications issues. Most PSAPs have a regional ESN, a number identifying the PSAP. A Service Access Point or SAP is an identifying label for network endpoints used in OSI networking. ... In the field of telecommunications, a telephone exchange (US: telephone switch) is a piece of equipment that connects phone calls. ...

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. For Wireline E911, the location is an address. For Wireless E911, the location is a coordinate. Not all PSAPs have the Wireless and Wireline systems integrated. A dispatch can be: A report sent to a newspaper by a correspondent. ... Computer-assisted dispatch (also called CAD) is a method of dispatching taxicabs, couriers, field service technicians, or emergency services by computer. ... MAP can refer to: Austronesian languages (ISO 639 alpha-3, map) Maghreb Arab Press, the News agency Malawi Against Polio Manifold absolute pressure, an important sensor in automobiles maximum a posteriori estimator, an estimator in statistics Missouri Assessment Program Mobile Application Part, an SS7-based protocol used in GSM networks...

Wireline Enhanced 911

There is special privacy legislation that permits emergency operators to obtain the caller's information. This information is gathered by mapping the calling phone number to an address and ESN in a database. This database function is known as ALI, Automatic Line Identification. The database is generally maintained by the Incumbent Local Exchange Carrier (ILEC) under contract by the PSAP. Each ILEC has their own standards for the formatting of the database. Most ALI databases have a companion database known as the MSAG, Master Street Address Guide. The MSAG describes the exact spelling of streets, street number ranges, and other address elements. ILEC or Incumbent Local Exchange Carrier is a local telephone company that was in existence at the time of the breakup of AT&T, for example, the Baby Bells and GTE. They compete with upstart Competitive Local Exchange Carriers. ...

Each telephone company (LEC) has at least two redundant DS0-level (that is, 64 kbit/s, or voice quality) trunks connecting each host office telephone switch to each PSAP. These trunks are either directly connected to the PSAPs or they are connected to a telephone company central switch that intelligently distributes calls to the PSAPs. These special switches are often known as 911 Selective Routers. Their use is becoming increasingly more common as it simplifies the interconnection between newer ISUP/SS7-based host office switches and the many older PSAP systems. Local exchange carrier is a regulatory term in telecommunications for so-called local telephone company. ... In T-carrier systems Digital signal 0 (DS0) is a basic digital signaling rate of 64 kbit/s, corresponding to the capacity of one voice-frequency-equivalent channel. ... In the field of telecommunications, a central office houses equipment that is commonly known as simply a switch, which is a piece of equipment that connects phone calls. ...

If the PSAP receives calls from the telephone company on older analog trunks, they are usually CAMA circuits. These circuits are similar to regular telephone lines, but are formatted to pass the calling party number. Plain old telephone service, or POTS, are the services available from analogue telephones prior to the introduction of electronic telephone exchanges into the public switched telephone network. ...

If the PSAP receives calls on older-style digital trunks, they are specially formatted Multi-Frequency (MF) trunks that pass ANI only. In telephony Multi-Frequency (MF) is an outdated, in-band signaling technique. ...

Some of the upgraded PSAPs can receive calls on ISUP trunks controlled by the SS7 protocol. In that case, the calling party number is already present in the SS7 setup message.The Charge Number Parameter contains the ANI.

The PSAP trunking does not pass address information along with the call. Instead, only the calling party number is passed. The PSAP uses the calling party number to look up the address in the ALI database. The ALI database is secured and separate from the public phone network by design.

ALI Failure is when the phone number is not passed or that the phone number is not in the ALI database. If this happens, the call is passed to the trunk group's default ESN, which is a PSAP designated for this function. The PSAP operator must then ask the incoming call for their location and redirect them to the correct PSAP. The legal penalty in most states for ALI database lookup failure is limited to a requirement that the telephone company fix the database entry. In mathematics, an operator is some kind of function; if it comes with a specified type of operand as function domain, it is no more than another way of talking of functions of a given type. ...

Competitive local exchange carriers (CLEC) and other competing wireline carriers negotiate for access to the ALI database in their respective Interconnect Agreement with the ILEC. They typically populate the database using the ILEC MSAG as a guide. A competitive local exchange carrier (CLEC), is a telecommunications provider company (sometimes called a carrier) that competes with other, already established carriers (generally the incumbent). ...

Wireless Enhanced 911

A second phase of Enhanced 911 service is to allow a wireless or mobile telephone to be located geographically using some form of radiolocation from the cellular network, or by using a Global Positioning System built into the phone itself. Cellular redirects here. ... Radiolocation is the process of finding the location of something through the use of radio waves. ... A cellular network is a radio network made up of a number of radio cells (or just cells) each served by a fixed transmitter, normally known as a cell site or base station. ... GPS satellite in orbit, image courtesy of NASA GPS redirects here. ...

Radiolocation in cellular telephony uses base stations. Most often, this is done through triangulation between radio towers. The location of the caller or handset can be determined several ways: Cellular redirects here. ... Base stations (or BSc) are low-power multi-channel two-way radios which are in a fixed location. ... Triangulation can be used to find the distance from the shore to the ship. ... Masts of the Rugby VLF transmitter in England Radio masts and towers are, typically, tall structures designed to support antennas (also known as aerials in the UK) for telecommunications and broadcasting, including television. ... In telephony and telecommunications, a caller, also known as the A-party, is the person or party who originates or dials a telephone call. ... A transceiver is a device that has a transmitter and receiver which is combined into a one unit. ...

• angle of arrival (AOA) requires at least two towers, locating the caller at the point where the lines along the angles from each tower intersect
• time difference of arrival (TDOA) works like GPS using multilateration, except that it is the networks that determine the time difference and therefore distance from each tower (as with seismometers)
• location signature uses "fingerprinting" to store and recall patterns (such as multipath) which mobile phone signals are known to exhibit at different locations in each cell

The first two depend on a line of sight, which can be difficult or impossible in mountainous terrain or around skyscrapers. Location signatures actually work better in these conditions however. TDMA and GSM networks such as Cingular and T-Mobile use TDOA. The term intersection can mean: a road junction, where two roads intersect each other, such as a roundabout intersection; in mathematics, the set in which two or more other sets intersect each other; see intersection (set theory); a movie; see Intersection (movie). ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... Multilateration, also known as hyperbolic positioning, is the process of locating an object by accurately computing the time difference of arrival (TDOA) of a signal emitted from the object to three or more receivers. ... Seismometer (in Greek seismos = earthquake and metero = measure) are used by seismologists to measure and record seismic waves. ... William West A story that some regard as apocryphal circulates about events occurring in the late 19th century when a man was spotted in the incoming prisoner line at the U.S. Penitentiary in Leavenworth, Kansas by a guard who recognized him and thought he was already in the prison... For the martial arts related meaning of Pattern see Tae Kwon Do and Kata (Karate). ... PRIMERGY MultiPath PRIMERGY MultiPath supports redundant Fiber Channel paths, the configured connections between server and subsystem that are such an important component of disaster-tolerant servers and clusters. ... When viewing a scene, as in optics, photography, or even hunting, the line of sight is the straight line between the observer and the target. ... Mount McKinley in Alaska has the largest visible base-to-summit elevation differences anywhere For other uses, see Mountain (disambiguation). ... Taipei 101, considered the worlds tallest skyscraper. ... Time Division Multiple Access (TDMA) is a technology for shared medium (usually radio) networks. ... Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ... Cingular Wireless is the largest United States mobile phone company, with headquarters in Atlanta, Georgia, United States. ... T-Mobile logo T-Mobile is a multinational mobile phone operator. ...

CDMA networks such as Verizon Wireless and Sprint PCS tend to use handset-based radiolocation technologies, which are technically more similar to radionavigation. GPS is one of those technologies. General Information Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference. ... Verizon Wireless, headquartered in Bedminster, New Jersey, owns and operates the second-largest wireless telecommunications network in the United States. ... This article is about the telecommunications company; see sprints for the running term. ...

Hybrid solutions, needing both the handset and the network include: In biology, hybrid has three meanings. ...

• assisted GPS (wireless or TV) allows use of GPS even indoors
• Advanced Forward Link Trilateration (A-FLT)
• Timing Advance/Network Measurement Report (TA/NMR)
• Enhanced Observed Time Difference (E-OTD)

The purpose of any of these in mobile phones is twofold: first, the wireless system must know to which PSAP it should route the call, and second, the PSAP that answers the call should know where the caller is and exactly where to send emergency services. GPS uses a network of 24 satellites to triangulate a receiver’s position and provide latitude and longitude coordinates. ... Wireless is an old-fashioned term for a radio receiver, referring to its use as a wireless telegraph; now the term is used to describe modern wireless connections such as in cellular networks and wireless broadband Internet. ... Braun HF 1, Germany, 1958. ... A telephone call is a connection over a telephone network between the calling party and the called party. ... Emergency services are services that deal with emergencies and other aspects of Public Safety. ...

Mobile phone users may also have a selection to permit the location information gathered to be sent to other phone numbers or data networks, so that it can help people who are simply lost or want other location-based services. By default, this selection is usually turned off, to protect privacy. A telephone number is a sequence of decimal digits (0-9) that is used for identifying a destination telephone line in a telephone network. ... Data is the plural of datum. ... A location-based service (or LBS) in a cellular telephone network is a service provided to the subscriber based on their current geographical location. ... Default is the name of a number of quite different concepts. ... Privacy is the ability of an individual or group to stop information about themselves from becoming known to people other than those they choose to give the information to. ...

VoIP Enhanced 911

Initial implementations of Voice over IP telephone systems were not integrated with the 911 system at all, meaning that customers could not even dial 911 in the event of an emergency. However, the Federal Communications Commission has mandated all VoIP providers to provide 911 service, including the E911 feature. A typical VoIP Solution A typical analog telephone adapter for connecting an ordinary phone to a VoIP network Voice over Internet Protocol (also called VoIP, IP Telephony, Internet telephony, and Digital Phone) is the routing of voice conversations over the Internet or any other IP-based network. ... The FCCs official seal. ...

On June 3, 2005, the FCC adopted rules requiring providers of VoIP services that connect with the traditional telephone network to supply E911 capabilities to their customers. The E911 hookup may be directly with the Wireline E911 Network, indirectly through a third party such as a competitive local exchange carrier (CLEC), or by any other technical means. The FCC explained that they felt compelled to issue this mandate because of the public safety concerns. (FCC, Notice of Proposed Rulemaking, WC Docket No. 05-196 available at [1]. Last visited September 18, 2005).)

There are, however, complicated technological problems with implementing E911 with VoIP, which providers are attempting to solve. For example, Vonage, has encouraged its customers to register their locations from which their 911 calls could be routed to the local public safety answering point. (Phil Weiser, Digital Crossroads, 2005, 222.) The FCC had continued to add more requirements and mandate a more sophisticated 911 function.

In some cases, VoIP providers are attempting to connect customers to E911 services through the traditional fixed-line telephone network, but the network is controlled by telecom carriers who are their economic competitors. (Grant Gross, FCC extends VoIP E911 deadline, August 26, 2005 available at [2] last visited September, 18 2005.)

In March, Texas Attorney General Greg Abbott filed a lawsuit against Vonage for deceptive marketing practices by not making it clear that VoIP users had to actually sign up for E911 service. Then in May, the FCC ordered VoIP providers to offer E911 service by late November. (Grant Gross, FCC extends VoIP E911 deadline, August 26, 2005 available at [3]. Last visited September, 18 2005.)

In June, 2005, the FCC announced that customers must respond to the E911 VoIP warning and those who do not have their service cut off on August 30, 2005. The FCC extended the deadline to September 28, 2005. (Gross - Ibid.) As of November 29, 2005, some VoIP providers were significantly out of compliance with the order. The FCC threatened to prevent these companies from marketing their services or signing up new customers in non-compliant areas. [4]

There are also other proposed features that are intended to allow telephone callers from large corporate telephone networks, on both traditional and VoIP PBXs, to be located down to the specific office on a particular floor of a building. PBX redirects here. ...

See also

• 9-1-1
• Craig Neidorf

Most emergency vehicles in the US and Canada display Emergency 911 9-1-1 (nine-one-one) is the emergency telephone number for the North American Numbering Plan (NANP). ... Craig Neidorf (1969), aka Knight Lightning, is a hacker, and one of the founding editors of Phrack. ...

External links

• FCC
  • Wireless 911 Services (FCC Consumer Facts)
  • Enhanced 911 - Wireless Services
• National Emergency Number Association
  • NENA document with diagram showing current and possible future system
• Law-review article providing background on VoIP technology and challenges of E911,