E911

(Enhanced 911) The 911 emergency service on cellular and Internet telephone calls (VoIP). In 1996, the FCC mandated a two-phase implementation for cellphone carriers to be completed by the end of 2005. Phase I required that carriers provide the telephone number and location of the cell tower that took the 911 call to the Public Safety Answering Point (PSAP). Phase II required that the carrier be able to triangulate the call to within 100 meters for the majority of calls. In 1999, the FCC added assisted GPS (AGPS) cellphones as an alternate solution with accuracy of 50 meters for the majority of calls.

In 2005, the E911 service requirement was mandated for voice over IP (VoIP) providers. See mobile positioning, triangulation and VoIP.