Indoor 911 Mobile Call Accuracy Goes Under Microscope

Verizon, AT&T, Sprint and T-Mobile partner on a road map to make continuing improvements in accuracy for 911 calls placed from inside structures.

Indoor 911 Mobile Call Accuracy

Emergency calls to 911 are mission-critical, but for callers who make 911 calls using mobile devices from inside structures built of concrete and steel, it can be difficult for 911 systems to accurately identify the precise location of the mobile caller.

That will hopefully change in the future as the big four U.S. wireless carriers—Verizon, AT&T, Sprint and T-Mobile—embark on a wireless indoor 911 location road map to together find ways to solve the technical problems that make indoor emergency calls so hard to locate when they come from mobile callers.

The new indoor mobile 911 road map agreement between the four companies was signed Nov. 14 and now is being used to plan out a strategy, milestones and technical means to find ways of solving the technical problems of locating such calls, wrote Steve Sharkey, T-Mobile's senior director of Government Affairs, in a Dec. 8 post on the T-Mobile Blog.

"Rather than merely extend the current approach of providing latitude and longitude coordinates to public safety, which doesn't provide the precise information needed by public safety to respond most effectively, especially in multi-floor and multi-unit buildings, this 'road map' agreement sets a fundamental new course," wrote Sharkey. "It leverages existing technologies, like WiFi and Bluetooth, to deliver an indoor caller's 'dispatchable location'—physical address including information such as floor, suite, or apartment—to the [Public Safety Answering Point (PSAP) equipment used for the service]. This allows public safety to benefit from the enormous resources that are continually invested in the ever-expanding commercial communications ecosystem."

The road map for this process is needed because cellular signals can't easily go through the concrete, steel and other building materials, making it hard to identify where indoor mobile calls originate from so they can be identified by 911 systems.

"T-Mobile is proud to be an architect of a landmark agreement between the four national wireless carriers and two major public safety organizations, NENA and APCO, to further improve location accuracy for 911 calls, including for calls made indoors," wrote Sharkey. NENA is the National Emergency Number Association, while APCO is the Association of Public-Safety Communications Officials International.

The indoor work for 911 calls coming from mobile users is the last big part of the technical puzzle that has been the emergency calling system in the past 20 years or more, he wrote.

"Over the past 20 years, wireless carriers, manufacturers, and the public safety community, have collaborated to develop solutions for a number of exceptionally difficult problems, including how to route cellular 911 calls to the correct public safety answering point (PSAP), to complete 911 calls for non-subscribers, and to allow first responders to locate callers who are unable to tell the PSAP where they are," wrote Sharkey. "As technologies and wireless coverage have improved, the carriers and PSAPs have continued to enhance these solutions, deploying increasingly robust location, routing and call completion capabilities."

The 17-page road map document calls for the partners to establish a test bed within 12 months to examine new techniques to improve mobile indoor caller location methods and create new standards for services. Among the techniques that could be further implemented are location-based services such as WiFi access points and Bluetooth beacons, which are used in more and more buildings.

One of the aims of the road map, which lists goals over the next four years and beyond, is to find indoor mobile locating methods that can pinpoint a caller's location within about 50 meters, according to the document.

"These significant and meaningful commitments recognize the challenges associated with providing accurate location information indoors, while spurring the deployment of new technologies and devices with improved location accuracy," the road map states.

"The road map's consensus approach provides the most effective wireless 911 solution, yielding concrete, measurable results long before we would have seen even modest improvements from the proprietary solutions being hyped by some vendors," wrote Sharkey. "NENA and APCO had the vision to push the carriers to go well beyond their comfort zones, resulting in an agreement that benefits both consumers and the first responders who serve them."

The FCC is now seeking public comment on the road map document.