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The nature of IP makes it difficult to locate network users geographically. Emergency calls, therefore, cannot easily be routed to a nearby call center. Sometimes, VoIP systems may route emergency calls to a non-emergency phone line at the intended department; in the United States, at least one major police department has strongly objected to this practice as potentially endangering the public.
A fixed line phone has a direct relationship between a telephone number and a physical location. If an emergency call comes from that number, then the physical location is known.
In the IP world, it is not so simple. A broadband provider may know the location where the wires terminate, but this does not necessarily allow the mapping of an IP address to that location. IP addresses are often dynamically assigned, so the ISP may allocate an address for online access, or at the time a broadband router is engaged. The ISP recognizes individual IP addresses, but does not necessarily know to which physical location it corresponds. The broadband service provider knows the physical location, but is not necessarily tracking the IP addresses in use.
There are more complications since IP allows a great deal of mobility. For example, a broadband connection can be used to dial a virtual private network that is employer-owned. When this is done, the IP address being used will belong to the range of the employer, rather than the address of the ISP, so this could be many kilometres away or even in another country. To provide another example: if mobile data is used, e.g., a 3G mobile handset or USB wireless broadband adapter, then the IP address has no relationship with any physical location, since a mobile user could be anywhere that there is network coverage, even roaming via another cellular company.
In short, there is no relationship between IP address and physical location, so the address itself reveals no useful information for the emergency services.
At the VoIP level, a phone or gateway may identify itself with a SIP registrar by using a username and password. So in this case, the Internet Telephony Service Provider (ITSP) knows that a particular user is online, and can relate a specific telephone number to the user. However, it does not recognize how that IP traffic was engaged. Since the IP address itself does not necessarily provide location information presently, today a "best efforts" approach is to use an available database to find that user and the physical address the user chose to associate with that telephone number—clearly an imperfect solution.
VoIP Enhanced 911 (E911) is a method by which VoIP providers in the United States support emergency services. The VoIP E911 emergency-calling system associates a physical address with the calling party's telephone number as required by the Wireless Communications and Public Safety Act of 1999. All VoIP providers that provide access to the public switched telephone network are required to implement E911, a service for which the subscriber may be charged. Participation in E911 is not required and customers may opt-out of E911 service.
One shortcoming of VoIP E911 is that the emergency system is based on a static table lookup. Unlike in cellular phones, where the location of an E911 call can be traced using Assisted GPS or other methods, the VoIP E911 information is only accurate so long as subscribers are diligent in keeping their emergency address information up-to-date. In the United States, the Wireless Communications and Public Safety Act of 1999 leaves the burden of responsibility upon the subscribers and not the service providers to keep their emergency information up to date.
Other articles related to "emergency, emergency calls, calls, call":
... The UK has two free emergency numbers—the traditional 999, which is still widely used, and the EU standard 112, which can be used in all member states of ... Both 999 and 112 are used to contact all emergency services Police, Fire Service, Ambulance Service, Mountain Rescue, Coastguard and Cave Rescue ... Although some mobile phones allow emergency calls to be attempted without a SIM card, at present the UK networks reject such calls ...
... Access Point Base Stations are also required, since carrying voice calls, to provide a 911 (or 999, 112, etc.) emergency service, as is the case for VoIP phone ...
... The first emergency number system to be deployed anywhere in the World was in London on 1 July 1937 using the number 999, and this was quickly extended to ... them involve long sequences of pulses, such as with the UK 999 emergency number ... as mobile phones will dial an emergency number while the keypad is locked or even without a SIM card ...
... 112 - main 01 - fire department 02 - police 03 or 113 - emergency medical service 04 - emergency gas service 112 calls are handled by the State Fire and Rescue Service ... If police or medical assistance is required, the call is redirected to the department the caller asks for ... In July 2010 the number 113 was introduced for emergency medical service, operated by State Emergency Medical Service of Latvia ...
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