s martbridge Trading Solutions Pvt. Ltd.

"Quick, call 911!" is a phrase that's uttered thousands of times each day. But calling 911 is a useless exercise unless one has a phone or other communications device that's capable of using the service.

 

E911 (enhanced 911) is a technology that's designed to give ordinary landline telephones the ability to transmit critical location data quickly and transparently, as well as to provide accurate emergency-calling capabilities to nontraditional-telephony devices such as mobile and VoIP phones. The technology automatically connects callers to the closest PSAP (public-safety answering point), the emergency-service dispatch centers that respond to 911 calls. There are more than 6,000 primary and secondary PSAPs across the U.S.

The need for E911 technology spiked when devices that don't use a dedicated phone line began gaining popularity. A mobile-phone user, for example, can be located virtually anywhere, making it impossible for a service provider to determine the location of the nearest and most appropriate PSAP. VoIP subscribers, on the other hand, often use phone numbers assigned to locations many miles away from their actual physical presences — sometimes even in other countries — also making it often impossible for service providers to supply an appropriate PSAP connection.

Landline E911

E911 became a reality more than two decades ago when the technology debuted on landline phones. All landline phones send an ANI (automatic number identification)signal to the network. Originally used to help carriers create accurate long-distance billing records, the ANI consists of eight digits: seven are the caller's local number, while the eighth digit represents a regional area code.

Utilizing ANI data, a PSAP can conduct a reverse-directory search to request and receive the caller's physical address. As a result, the PSAP doesn't have to depend on the caller for location and callback information. The dispatcher can instead focus on helping the caller through the crisis, while quickly passing along relevant information to the appropriate public-safety authorities.

Wireless E911

Facing increasing pressure from mobile-phone customers for an effective, reliable 911 calling system, the   began taking steps in the late 1990s to force mobile carriers to adopt a wireless E911 strategy. The FCC deployed its E911 plan in two phases. In 1998, Phase I required carriers to deploy an E911 service that could identify the originating phone numbers of all 911 calls, as well as the location of the associated cell tower to within one mile. In 2001, Phase II mandated every mobile carrier offering service within the U.S. to provide either a handset- or network-based location-detection capability. The ALI (automatic location identification) service had to be able to determine an E911 caller's location by the geographic position of the mobile phone within 100 meters, and not simply by the location of the associated cell tower. This is usually accomplished by triangulating the signals of three or more nearby cell towers.