9-1-1 Technology

A 9-1-1 call made from a home landline phone is routed through the telephone company which delivers the call to the appropriate PSAP (Public Safety Answering Point) based on the location of the call. It obtains the location of the call through a database containing address information for all landlines registered with the telephone company.

Wireless calls are routed using the cell tower sectors, depending on the PSAP designated to that sector.  Location of wireless calls can vary due to the technology used to triangulate the device’s location.  It will continue to obtain the best coordinates to assist telecommunicators with up-to-date location. Texting to 9-1-1 on a wireless device is available in some areas and can be used in situations when calling is not an option.

The telecommunicators are delivered 9-1-1 calls with the best available location information but are always trained to confirm what they receive to aid first responders.  Telecommunicators’ 9-1-1 software will display caller information with the location as well as a detailed map with the caller’s location using mapping software.  Mapping software presents the location and allows the telecommunicator to assist first responders in navigating to the caller’s location.  Some mapping software will also allow the telecommunicator to select the first responder personnel closest to the caller’s location for a more rapid response.

Location occurs from the Automatic Location Identification, or ALI, received during a 9-1-1 call as the system initiates a query to the ALI database.  On wireless calls, location received by the cellular service company, using triangulation, is given in the format of XY coordinates.  When XY coordinates are unavailable, the cell tower’s address is provided as a location.

A misconception about 9-1-1 calls is that the location received is always correct and precise. The telecommunicator should always confirm the location of the call to rule out any errors.

9-1-1 circuits are often busy with numerous calls which means telecommunicators will always try to keep the lines clear by requesting you call a non-emergency line.

Future technologies under development will help the 9-1-1 system be more efficient in serving the public.  Technologies include: more accurate location services for wireless calls utilizing the technology that exists on the cell phone;  enhanced media for Text-to-911 calls (the ability to attach voice, video and pictures to an emergency situation text message);  and the ability of 9-1-1 telecommunicators to text from 9-1-1 centers in emergency situations.


Celebrating 50 Years of 9-1-1

AT&T Honors 50 Years of 9-1-1