E911 Protocol
Law enforcement and emergency response personnel can use your cell phone data to triangulate your approximate position, helping them find you if you make an emergency call and then drop your phone for any reason. Although not extremely accurate, your phone data provides a silent beacon to public safety answering points -- the 911 call centers -- when making an emergency call. Enhanced from the basic and revised 1998 Phase I standard, E911 Phase II standards -- ratified in 2001 -- move beyond providing simple phone number and cell tower data. Phase II requires cell phone providers to provide emergency personnel with actionable data when an emergency call is placed. Latitude and longitude information helps emergency responders to better locate the phone -- and presumably the caller -- more accurately than before.
Provider Compliance
The FCC mandates that as of 2011 all cell phone service providers over an eight-year period provide information about coverage areas they intend to exclude from location services. However, these exclusions are only county-by-county, and have proven environmental issues precluding accurate tracking of cellular data. Such areas include dense wilderness or areas that lack cell tower triangulation capability. These exclusions are reported to the FCC and are publicly reviewable.
ALI Technology
Every phone sold provides automatic location identification. This program mandated that all emergency cell phone services achieve 95 percent market penetration by 2002. Cell phone carriers implement location services in two primary ways, affecting ALI accuracy. Using handset-based services, ALI emergency call data accuracy is 50 meters for 67 percent of calls, or 150 meters for 95 percent. For network-based calls, this requirement is modified to 100 and 300 meters, respectively. ALI constantly provides cell phone providers with geotagging data, monitoring physical location of enabled phones whether the user turns GPS services on or not.
PSAPs
Public safety answering points are standalone monitoring and answering centers that receive emergency cell phone calls. PSAP personnel relay emergency information to the appropriate emergency service providers through voicemail, text or other broadcasting methods. Although cell phones and providers must provide GPS location of the phone to PSAPs, these stations are not legally bound to receive it. PSAPs are governed by local and state authorities, often sharing emergency services between fire, police and ambulance.
Considerations and Future Improvements
Whenever an emergency phone call is made, you should never assume the person on the other end has any idea where you are. Providing your location, including main and cross streets, is necessary to get the most accurate response. Learning your state's emergency numerical code system helps direct phone calls to appropriate call centers without additional delay. You should also provide your return phone number if you're disconnected, especially if you are calling from a cell phone not currently under contract. Although texting and sending pictures is not currently supported, these improvements are expected as the emergency standards evolve, according to the FCC's Five Step Action Plan, released in August of 2011. Texting is useful in those cases where a caller cannot speak without risking further injury or revealing his location to an attacker. Pictures would help emergency personnel evaluate the situation, allowing better preparation prior to arrival.
