Locating emergency calls
When cell phone users in Downey, Calif., called 911 in January, emergency dispatchers were able to see the callers’ locations on computer maps for the first time. As a result, the Downey Police Department’s Communications Center became the first Southern California public safety answering point (PSAP), and the second in California, to comply with Phase II Wireless E911 mandates.
In June 1996, the Federal Communications Commission required that wireless phone users receive the same enhanced 911 (E911) service that is available to landline callers, which means the phone number and the address from which the 911 call is made is transmitted to the PSAP. The Wireless E911 mandate was divided into two phases: Phase I required wireless service carriers to transmit the wireless phone numbers and the addresses of the cell towers closest to the 911 callers; Phase II required wireless service carriers to be more specific and transmit the latitude and longitude of the phones. To comply with Phase II, cell phone service providers can install global positioning system (GPS) units in the phone handsets or change their cellular networks to triangulate callers’ locations from the three nearest cellular towers. PSAPs that choose to receive wireless calls’ location information must have mapping software that can display those locations.
When cellular telephone service was introduced in the 1980s, the California Highway Patrol (CHP) was responsible for answering all wireless 911 calls because the majority of them were made from freeways. If wireless 911 calls originated from outside of the CHP’s jurisdiction, dispatchers would transfer the calls to the nearest responding local public safety agencies.
By January 2001, California PSAPs could choose to receive wireless 911 calls directly, and CHP and the state Department of General Services 9-1-1 Program Office began transferring the responsibility for answering them. At that point, the local PSAPs needed software that could comply with Phase I or Phase II of the Wireless E911 FCC order.
In September 2002, the Downey PSAP upgraded its legacy dispatch software to a computer-aided dispatch (CAD) and records management system from Troy, Mich.-based New World Systems. In the beginning, dispatchers could see maps and the locations of calls coming only from landline phones, but soon the cellular phone companies routed the wireless 911 calls from the CHP to the Downey PSAP. By spring 2003, the city was receiving calls from wireless phones, and dispatchers’ CAD maps could show the latitude and longitude of the cell site that was closest to the caller. By January, AT&T, Verizon and Sprint PCS had altered their wireless systems in the area so that the department could pinpoint cell phone callers if they were using Phase II-compliant phones that transmit latitude and longitude coordinates. Based on those coordinates, dispatchers can tell responding officers the nearby addresses of callers.
The call load for the Downey PSAP has increased as a result of accepting the cell phone calls directly, but the load has not been overwhelming, according to Dispatch Supervisor Heidi Calhoun. “It’s not that big of an increase in call volume, so it’s definitely worth it to provide the callers and the citizens with immediate help,” she says.
