Enhanced 911
![]() | It has been suggested that Next Generation 9-1-1 be merged into this article. (Discuss) Proposed since January 2024. |
Enhanced 911 (E-911 or E911) is a system used in North America to automatically provide the caller's location to
when called by a vehicle.An incoming 911 call is routed to a
Call routing
Landline routing
Calls to 911 over the public switched telephone network (PSTN) are routed to a special router (known as Selective Router, or 9-1-1 Tandem).[3][4] The router looks for the address associated with the caller's telephone number in a database. The caller's phone number is known as an ANI. The database relating ANIs to addresses is known as ALI (Automatic Location Identification). The router then uses the address to search in the MSAG for the Emergency Service Number (ESN) of the appropriate PSAP for that area and connects the call to it.[5][6]
MSAG
The Master Street Address Guide (MSAG) is a database of street addresses and corresponding Emergency Service Numbers (ESNs).[7] ESNs represent one or more emergency service agencies (e.g. fire department, law enforcement) designated to serve a specific range of addresses in a geographic area, called an Emergency Service Zone.[8]
Wireless routing
Calls from cellular phones are received via cell towers by mobile switching centers (MSC).[6] The switching center automatically assigns a unique identifier to each cellular 911 call, known as a "pseudo ANI".[6] The Selective Router connects the call to a PSAP based on the cell tower's location.[6]
Location transmission
Calls made to non-911 emergency numbers (such as the direct line to a police or fire department) might not have automatic location enabled.
Calls to 911 are answered by an operator at a PSAP. In addition to the voice transmission, the telephone network also transmits a number associated with the current call, the ANI. The 911 operator (or their computer) at the PSAP searches a database (ALI) for the ANI to find the caller's location.
The ALI record associated with the query is then returned to the PSAP, where the Customer-premises equipment (CPE) correlates that information with the call taker receiving the call, and displays the information on their computer screen.
Automatic location of the emergency is intended to be faster and more reliable than verbal communication of the location, though this is usually requested anyway for confirmation. It also makes it possible for emergency services to respond when callers cannot communicate their location, because they do not know their location, they are a child, or they are too panicked, too distracted by the ongoing emergency, or do not wish to attract the attention of the perpetrator of a crime in progress.
Landline transmission
For landline calls the ANI resembles the caller's phone number. The ALI stores a pre-determined address associated with the caller's telephone number. This address is typically the phone's billing address.[2]
Wireless transmission
In parallel to the actual voice call, the ALI database gets periodically updated with more precise and recent location information.[6] Cellular networks can determine a more precise location of the caller's device by using triangulation from the cell towers (radiolocation). In addition to triangulation, a second source of location information may be the caller's phone itself (or other cellular device).
Many phones manufactured after 2005 have GPS receivers built in.[9] 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 manufacturers may program the phone to enable GPS function automatically (in case it has been turned off) when the user places an emergency call.[10]
For wireless calls, the ANI (or "pseudo-ANI") is a unique number assigned to each individual 911 call, assigned at a mobile switching center.[6]
ALI database
![The 911 system](http://upload.wikimedia.org/wikipedia/commons/thumb/6/65/9-1-1_System.svg/500px-9-1-1_System.svg.png)
The ALI database is secured and separate from the public phone network by design.
The ALI is maintained on behalf of local governments by contracted private third parties, generally the
Each ILEC has its own standard 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. When a new account is created, the address is located in the Master Street Address Guide to track the proper Emergency Service Number (ESN) that 911 calls from that phone number should be routed to. 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 populate the database using the ILEC MSAG as a guide.
If the phone number is not in the ALI database, this is known as ALI Failure; the call is then passed to default ESN for the call's
Location determination
The way location is determined varies by the type of originating device or network.
Landline location
Landline or wireline calls originate from a device connected to a known and fixed location connection to the PSTN. These locations are stored in the Automatic Location Information (ALI) database.[1] This is permitted by special privacy legislation.
Location information is not passed along by the public phone network; only the calling party's phone number is known to the receiver.
Wireless location
The billing address associated with a
To locate a mobile telephone geographically, there are two general approaches. One is to use some form of radiolocation from the cellular network; the other is to use a Global Positioning System receiver built into the phone itself. Both approaches are described by the Radio resource location services protocol (LCS protocol).
Radiolocation in
- intersect.
- 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 T-Mobile 2G use TDOA.[11] AT&T Mobility initially advocated TDOA, but changed to embedded GPS in 2006 for every GSM or UMTS voice-capable device due to improved accuracy.
Hybrid solutions, needing both the handset and the network include:
- Assisted GPS (wirelessor television) 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)
Mobile phone users may also have a selection to permit location information to be sent to non-emergency
The
911 address
The term 911 address refers to a format for specifying where a 911 call originated from (e.g. the address of the landline, or estimated location of a cell phone).
The 911 address contains a uniform number, the street name, direction (if applicable), and the city. The uniform number is usually assigned by the grid of the existing community. Each county usually has their own policy on how the addressing is done, but for the most part NENA guidelines are followed.[citation needed] These guidelines are expressed by the Master Street Address Guide (MSAG). The exact 911 addresses and associated phone numbers are put into the ALI database.
History
The first 911 system was installed in
.The 911 Act
In the US, the
FCC Requirements
The U.S. Federal Communications Commission (FCC) has made several requirements applicable to wireless or mobile phones:[12]
- Basic 911: All 911 calls must be relayed to a call center, regardless of whether or not the mobile phone user is already a customer of the network being used.[13]
- E911 Phase 1: Wireless network operators must identify the phone number and cell phone tower used by callers, within six minutes of a request by a PSAP.
- E911 Phase 2:
- 95% of a network operator's in-service phones must be E911 compliant ("location capable") by December 31, 2005. (Numerous carriers missed this deadline and were fined by the FCC.[14])
- Wireless network operators must provide the latitude and longitude of callers within 300 meters, within six minutes of a request by a PSAP.[15] Accuracy rates must meet FCC standards on average within any given participating PSAP service area by September 11, 2012 (deferred from September 11, 2008).[16]
Location information is used by the wireless network operator to determine to which PSAP to route the call to, and is transmitted to the PSAP for the purpose of sending
In 1996, the U.S.
The order also laid out milestones for implementing wireless location services. The first Phase I wireless 911 call was in September 1997 in
In July 2011, the FCC announced a proposed rule requiring that after an eight-year implementation period, at some yet-to-be-determined date in 2019, wireless carriers will be required to meet more stringent location accuracy requirements. If enacted, this rule would require both "handset based" and "network based" location techniques to meet the same accuracy standard, regardless of the underlying technology used. The rule is likely to have no effect as all major carriers will have already achieved over 85% GPS chipset penetration, and are thus able to meet the standard regardless of their 'network based' location capabilities.[7][needs update]
In Canada
In 2009, the Canadian Radio-television and Telecommunications Commission (CRTC) required implementation of Phase II Stage 1 for wireless carrier by 1 February 2010, in areas that provide landline E911.[10] Many Canadians now have access to Phase II service.[18]
Public-safety answering point (PSAP)
The final destination of an 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 (Emergency Service Zone) covered by a single PSAP is based on the dispatch and response arrangements for the fire, police, and medical services for a particular area. All primary PSAPs have a regional Emergency Service Number (ESN), a number identifying the PSAP.
The Caller Location Information (CLI) provided is normally integrated into emergency
Interconnection details
Each telephone company (
If the PSAP receives calls from the telephone company on older analog trunks, they are usually
If the PSAP receives calls on older-style digital trunks, they are specially formatted
VoIP enhanced 911
VoIP enhanced 911 pertains to communications originating from various commercial services provided by companies that send telephone calls across the commercial internet using specialized devices and software applications.
As
The
Initially, the U.S. Federal Communications Commission (FCC) took a hands-off approach to VoIP in order to let the service mature, and also to facilitate competition in the telephony market.[21] In time, this problem reached the headlines of newspapers as individuals were unable to place emergency calls with their VoIP phones. In March 2005, 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.[22]
When FCC Chair Kevin Martin replaced FCC Chair Michael Powell, he immediately changed FCC's hands-off policy and moved to impose 911 obligations on VoIP service providers.[23] In 2005, Chair Martin moved FCC to require "interconnected VoIP services" to begin to provide 911 service and provide notice to their consumers concerning the 911 limitations. 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.[24] 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.[25] Vonage co-founder Jeff Pulver opined that this was an attempt by FCC Chair Martin to hinder telephony competition to AT&T.[26]
The 911 obligations were imposed only on "interconnected VoIP." The FCC defined "interconnected VoIP" as VoIP over broadband that interconnects with the public switch telephone network.[27] VoIP that is not interconnected, such as two individuals talking to each other over the Internet while playing computer games, does not fall under the obligation.
There are, however, complicated technological problems with implementing E911 with VoIP, which providers are attempting to solve. VoIP phones are on the Internet and nomadic; the
VoIP services have noted an obstacle to full 911 interconnection; in order to interconnect with the Public Safety Answering Point, the VoIP service providers must interconnect with the 911 telephone trunk, which is owned and controlled by their competitors, the traditional fixed-line telephone carriers.[24] This resulted in the New and Emerging Technologies 911 Improvement Act of 2008 which granted interconnection rights to interconnected VoIP services.[33]
In response to the E911 challenges inherent to IP phone systems, specialized technology has been developed to locate callers in the case of emergency. Some of these new technologies allow the caller to be located down to the specific office on a particular floor of a building. These solutions support a wide range of organizations with IP telephony networks. The solutions are available for service providers offering hosted
In recent years there have been numerous important developments in E911 solutions for IP phone technology. The more noteworthy of these developments include:
- On-site appliances that automate and simplify E911 management for enterprise IP-PBX systems, reducing administration, ensuring that IP phone locations are always up to date, thus helping enterprises meet their E911 obligations;
- IP phone tracking that automatically assigns locations to IP hard phones, soft phones and wireless phones as they move on the corporate network using layer 2, layer 3, or wireless LAN discovery.
- Support for remote employees, allowing off-campus users and teleworkers to update their locations in real time directly from their IP phones;
- Support for phone mobility, to ensure accurate E911 services for employees that move IP phones between locations, share line appearances between multiple devices, and log into IP phones on the fly;
- Security desk routing and notification functionalities that deliver 911 calls and custom email alerts to on-site security personnel, notifying them of the emergency and providing them with the caller’s precise location information;
- Advanced E911 call management and reporting features, such as misdial protection and call recording, to improve solution performance and administration.
VoIP & 911 issues are also relevant to
Multi-line Telephone System
Multi-line Telephone System (MLTS) pertains to the location of callers dialing 911 from within the private telecommunications networks used by large organizations. A Multi-line Telephone System (MLTS), often referred to as a
The challenge of Enhanced 911 for the MLTS is that information about the location of callers is only available to the extent that the private organization discloses the information. For the organization the challenges of collecting and reporting the information can be significant. Today’s highly mobile work forces and technologies that allow users to relocate without the intervention of an administrator place significant responsibilities on the MLTS owner or operator.
MLTS Legislation
On August 1, 2019, the FCC adopted a Report and Order to address calls to 911 made from multi-line telephone systems (MLTS) that commonly serve hotels and office buildings, pursuant to Kari’s Law. The Report and Order also addressed sending dispatchable location information with 911 calls, and consolidating the FCC’s 911 rules.[35]
Under the provisions outlined in KARI'S LAW, new and upgraded MLTS systems after February 17, 2020 must:
- Enable the public to dial 911 from MLTS directly, without having to dial additional numbers, such as a “9,” to reach an outside line.
- Require MLTS to send a notification to a location where someone is likely to hear or see it when a 911 call has been made.
In addition to Kari's Law, §506 of the RAY BAUM'S Act[36] adds the requirement that by January 6, 2021, wired MLTS devices must:
- Establish dispatchable location information requirements for 911 calls from MLTS, fixed telephone services, interconnected Voice over Internet Protocol (VoIP) services, mobile text, and Internet-based Telecommunications Relay Services (TRS).
WIRELESS devices have an additional year to be made compliant.
Dispatchable location is defined as: The street address of the calling party Information SUCH AS room number, floor number, or SIMILAR INFORMATION necessary to adequately identify the location of the calling party.
In a recent Podcast recorded at the NENA 911 Goes to Washington event in WASHINGTON, DC, David Furth, the Deputy Director of Public Safety and Homeland Security provided a recap of the legislative actions.[37]
The legislation does over rule any current State legislation, that currently exists in numerous US government jurisdictions, unless the Federal requirements are more restrictive. The burden still remains upon the enterprise organization to provide compliance when an emergency call originates from within a MLTS system, however the new language also adds responsibility to Manufacturers, Importers, Distributors, and Installers as well s the person who owns, operates. rents, buys or leases the system.
The member driven volunteer organization that represents the people who staff the PSAPs, the National Emergency Number Association (NENA.org), has done significant work advocating on the subject of MLTS E911. Hank Hunt, Kari Hunt's father has championed the legislation, named after his late daughter, which started as a promise to his granddaughter who knew to dial 9-1-1 from the hotel room phone, but had no idea the phone needed a 9 to dial an outside line. Hank is carrying on the legacy of Kari and is a popular speaker at Public Safety and Telecom shows and events. His actions are funded through The Kari Hunt Foundation, a 501(c)(3) non-profit.[38]
It is an important contemporary issue of growing concern as enterprise style organizations employ new technologies to create vast private networks that interconnect with the PSTN in ways that do not map to the logic used to locate callers in the Public Enhanced 911 system. The risks to people who initiate a 911 call from an MLTS who are not physically located within the jurisdiction of the agency to which the 911 call is routed and the increasing burdens of misdirected 911 calls upon those agencies is escalating.
The FCC Report and Order outlines the actions taken:[39]
Address signage standards
In addition to upgrading communications systems, some counties and communities in the United States have established ordinances (e.g. IRC section R319.1) requiring property owners to standardize the display of house numbers on buildings and along streets and roadways, to allow emergency personnel to more easily identify a given address day or night, even in poor weather. These are normally composed of reflective characters, at least 3 to 6 inches high, on a contrasting reflective background. It is necessary for the address number to be affixed to the building or to a separate structure such as a post, wall, fence, or mailbox, provided that such separate structure is located in front of the building and on the building's side of the street. Compliant signage systems are often advertised as being "E911 compliant".[citation needed]
Privacy concerns
The FBI CAST Cellular Analysis & Geo-Location Field Resource Guide[40] reveals that wireless carriers in the U.S. routinely activate E911 functionality on their customers' mobile phones for the purposes of tracking their locations without their permission, as of March 2019. Telecommunications companies then provide this location data to various government agencies that request it, making it clear that use of E911 functionality is not limited to emergencies and that the technology is often implemented in such a way that tracking can be remotely activated without the user's knowledge or consent.
Cultural references
John McAfee @officialmcafee The "Presidential alerts": they are capable of accessing the E911 chip in your phones - giving them full access to your location, microphone, camera and every function of your phone. This not a rant, this is from me, still one of the leading cybersecurity experts. Wake up people!
3 October 2018[41]
After a national test of Wireless Emergency Alerts (live since 2012) on 3 October 2018, a number of rumours and false statements spread on social media. Among them a tweet by John McAfee that went viral, in which McAfee claimed that the "Predentials alert" involved the E911 system, and that smartphones have a "E911 chip" capable of giving the government access to the phone's location and microphone.[42][43] The Electronic Frontier Foundation reported that there is "no such thing as an E911 chip".[2] Fact-checking website Snopes stated that "WEA messages are not [related] to E911 functions".[44]
See also
- Advanced Mobile Location
- eCall
- Emergency Medical Dispatcher
- GPS tracking
- Mobile phone tracking
- Next Generation 9-1-1
- Northern 911
- Reverse geocoding
- Text-to-911
- Triangulation
- Voice Over Internet Protocol
References
- ^ a b "What is an ALI Database? - Bandwidth". Bandwidth. Retrieved 2018-10-05.
- ^ a b c Quintin, Cooper (2018-10-04). "There are Many Problems With Mobile Privacy but the Presidential Alert Isn't One of Them". Electronic Frontier Foundation. Retrieved 2018-10-08.
- ^ "911 Master PSAP Registry". Federal Communications Commission. 2011-02-14. Retrieved 2018-10-08.
- ^ "Communications Route Diversity for Public Safety". Federal Communications Commission. 2011-02-11. Retrieved 2018-10-08.
- ^ "ECN 911 History". Minnesota Department of Public Safety. Retrieved 2018-10-08.
- ^ a b c d e f US 20160337831A1, "Real-time over the top 9-1-1 caller location data", published 2016-11-17
- ^ a b "FCC 11-107, Notice of Proposed Rulemaking" (PDF). Retrieved 2013-01-11.
- ^ PSAP Installation Guide (19 December 2011), ECN 911 Program, Minnesota Department of Public Safety
- ^ "How GPS Phones Work". HowStuffWorks. 2005-10-24. Retrieved 2018-10-05.
- ^ a b "Telecom Regulatory Policy CRTC 2009-40". Canadian Radio-television and Telecommunications Commission. 2009-02-02. Retrieved 2013-02-20.
All wireless service providers are to complete their respective implementation of wireless Phase II Stage 1 E9-1-1 service by 1 February 2010, wherever wireline E9-1-1 service is available across Canada.
- ^ a b "FCC Report to Congress on the Deployment of E-911 Phase II Services by Tier III Service Providers" (PDF). Federal Communications Commission. April 1, 2005. Retrieved 2010-11-18.
- ^ "Wireless 911 Services". Consumer & Governmental Affairs Bureau. FCC.gov. Retrieved 2010-11-18.
- ^ "E911 Turns Cell Phones into Tracking Devices". WIRED. 6 January 1998. Retrieved 2018-10-05.
- ^ "Sprint, Alltel, USC fined for missed e911 deadline". FierceWireless. 2007-08-31. Retrieved 2010-11-18.
- ^ "How accurate E911?". GPS World. Questex Media Group, Inc. November 2007. Archived from the original on 2012-07-08. Retrieved 2010-11-17. Network-based technology:100 meters for 67% of calls and 300 meters for 95% of calls. Handset-based technologies: 50 meters for 67% of calls and 150 meters for 95% of calls.
- ^ "Carriers push E-911 lawsuit in court despite winning deadline extension". RCR Wireless News. 2008-03-14. Retrieved 2010-11-18.
- ^ "History of 9-1-1". City of Allentown. Archived from the original on 2019-08-27. Retrieved 2019-08-27.
1997: First Phase I Wireless 9-1-1 call in the United States, made in the City of Allentown during a trial project with CellularOne and XYPoint.
- ^ See also the third and fourth paragraphs of
- ^ "911 Mapping Systems, Inc". 911mapping.com. Archived from the original on 2006-03-23. Retrieved 2010-11-18.
- ^ "Obituary: Robert Thomas Jr., 911 Mapping CEO". Enquirer.com. 2002-12-25. Archived from the original on 2012-07-29. Retrieved 2010-11-18.
- ^ "In the Matter of Federal-State Joint Board on Universal Service, Report to Congress, Docket 96-45" (PDF). FCC. April 10, 1998. p. 42.
- ^ OAG (2005-03-22). "Attorney General Abbott Takes Legal Action To Protect Internet Phone Customers" (Press release). OAG.state.tx.us. Archived from the original on March 23, 2005. Retrieved 2010-11-18.
- ^ "Why Does the FCC Treat VoIP as the Ugly Duckling, Techdirt July 25, 2006". Techdirt.com. 2006-07-25. Retrieved 2010-11-18.
- ^ a b Gross, Grant (August 26, 2005). "FCC extends VoIP E911 deadline". PCWorld.com. Archived from the original on February 22, 2006. Retrieved 2010-11-18.
- ^ "IP-Enabled Services: E911 Requirements for IP-Enabled Service Providers" (PDF). FCC. May 19, 2005. Archived from the original (PDF) on 2011-10-21. Retrieved 2010-11-18.
- ^ Pulver, Jeff (July 24, 2006). "A Little Rant on the Ongoing Mis-application of CALEA and E911 and Universal Service on Voice Applications and Some Ironic, Illogical Results". Jeff Pulver Blog. Archived from the original on March 9, 2011. Retrieved 2010-11-18.
- ^ Cannon, Robert. "VoIP Definition :: FCC :: Interconnected VoIP :: CFR". Cybertelecom.org. Retrieved 2010-11-18.
- ^ Currier, Bob (2010-06-21). "Intrado Evolution of the PSAP Experience - Slide 0" (PDF). Archived from the original (PDF) on May 18, 2006. Retrieved 2010-11-18.
- ^ Meer, Stephen; Nelson, Michael (May 2004). "Intrado Next Generation Needs" (PDF). Archived from the original (PDF) on June 26, 2007. Retrieved 2010-11-18.
- ^ "Intrado Emergency Calling Services" (PDF). Archived from the original (PDF) on May 18, 2006. Retrieved 2010-11-18.
- ISBN 9780262140911.
- ^ "Answering the Call for 911 Emergency Services in an Internet World" (PDF). Voice on the Net Coalition. January 2005. p. 4. Archived from the original (PDF) on 2005-01-23.
- ^ "VoIP :: 911 :: Regulation". Cybertelecom.org. Information on NET Act and FCC proceeding implementing legislation.
- ^ "Emergency Gateway Datasheet" (PDF). 911 Enable. Archived from the original (PDF) on 2012-09-14.
- ^ "FCC Amends Rules to Improve Access to 911". Federal Communications Commission. 2019-08-06. Retrieved 2020-02-29.
- ^ Blackburn, Marsha (2018-03-07). "Text - H.R.4986 - 115th Congress (2017-2018): RAY BAUM'S Act of 2018". www.congress.gov. Retrieved 2020-02-29.
- ^ "TiPS with David Furth Deputy Director of the FCC PSHSB on 911 Legislation". Spreaker. Archived from the original on 2020-02-29. Retrieved 2020-02-29.
- ^ "Kari Hunt Foundation - Home". karihuntfoundation.org. Archived from the original on 31 July 2020. Retrieved 14 January 2022.
- ^ "Implementing Kari's Law and Section 506 of RAY BAUM'S Act | PS Docket No. 18-261, et al" (PDF). fcc.gov. August 2, 2019. Retrieved 2020-02-29.
- ^ "FBI CAST Cellular Analysis & Geo-Location Field Resource Guide". Property of the People. 2021-10-19. Retrieved 2021-10-25.
- ^ John McAfee [@officialmcafee] (October 3, 2018). "The "Presidential alerts": they are capable of accessing the E911 chip in your phones - giving them full access to your location, microphone, camera and every function of your phone. This not a rant, this is from me, still one of the leading cybersecurity experts. Wake up people!" (Tweet) – via Twitter.
- ^ "The presidential text alert system is rife for conspiracy theories". The Daily Dot. 2018-10-06. Retrieved 2021-11-13.
- ^ "John McAfee's Presidential Alert Tweet on E911 Chip Explained!". Earn The Necklace. 2018-10-05. Retrieved 2021-11-13.
- Snopes.com. Retrieved 2021-11-13.
External links
- Wireless 911 Services - FCC Consumer Facts
- Enhanced 911 - Wireless Services
- National Emergency Number Association Archived 2005-02-23 at the Wayback Machine
- Law-review article providing background on VoIP technology and challenges of E911, locating VoIP Callers and prioritizing Emergency traffic in the VoIP Network.
- Cybertelecom - VoIP and 911 - Federal Internet Regulation
- E9-11 Institute - E-911 Education Organization
- How E-911 caller locations are discovered
- Emergency Calling for SIP