Why Locating 911 Calls Is So Hard—And How To Make It Better

You've heard the cautionary tales about dialing 911 on your cell phone. A call about missing children in Illinois gets routed to Canada. A stroke victim in New York is only located after a grueling eight-hour search. Locating 911 calls in 2014 is a byzantine process that involves generating a fake phone number—but a Next Generation 911 system that integrates text and video is in the (somewhat) near future, if we can only can get our collective shit together.

The problem, which, in some ways, is a good problem, is that phone technology keeps improving. As we get novel technologies like mobile phones or voice over IP (VoIP), dispatchers have to play a long, painful game of catch up. Integrating the databases of local governments with telecommunications companies is a slow-moving affair.

Even automatically linking landlines with home addresses took until the 1980s. "Just as emergency responders got used to getting all this information, however, the appearance of mobile phones plunged them back into darkness," write Richard Barnes and Brian Rosen in a technical but fascinating history of locating 911 calls for IEEE Spectrum.

How 911 Calls from Mobile Phones Are Tracked

The FCC estimates that 70 percent of 911 calls are now made on mobile phones. To get mobile phones working with the existing dispatch system, phone companies had to create either a Mobile Positioning Center or Gateway Mobile Location Center, which tries to find the phone and literally assigns it a pseudo phone number related to its location. Here's how it then works, according to Barnes and Rosen:

At the emergency communications center, the database flags the call as coming from a pseudo number and identifies the Mobile Positioning Center or Gateway Mobile Location Center that assigned it. The system then sends the query along to the correct positioning center or location center, which tries to figure out the cellphone's location by collecting its GPS coordinates or calculating its location by comparing the strength of the signals coming from several points—that is, by triangulation. If the system can't do that, say, because the GPS signals are blocked, or too few towers are able to measure signals from the phone to provide coordinates for triangulation, it instead sends the street address of the cell tower. That, however, may not be particularly useful, because the caller could be several kilometers away.

Last year, a report found that 55 percent of 911 calls made with a cell phone in California could, in fact, only be tracked to its nearest cell tower—possibly miles from the phone's actual location. After that report caused understandable alarm, agencies from seven other states audited their calls to find similar blackouts, with up to two-thirds of 911 calls never tracked to a specific spot.

Indoor 911 calls from a multi-story building are especially frustrating. In February, the FCC proposed rules requiring wireless phone companies to get better at locating indoor calls within five years. The companies responded by saying the technology was not available. Except, of course, our cell phones already use Wi-Fi hot spots to quite accurately determine our location. Hot spot databases are private, however, and they would have to be rigorously tested before they can be used for emergency dispatching. As the New York Times notes, "the last round of F.C.C. requirements for 911 calling data was established in 1996. But it will not be fully carried out until 2019." Who knows how long this will take.

A Grand New Plan?

In an even more ambitious effort that began in 2000, regulators have been planning Next Generation 911. While the old system forced mobile phones to get fake numbers to just get into the dispatch system, NG911 is designed specifically for wireless calling and operates over an IP network.

In its conception, NG911 is a complete overhaul of the entire 911 system that will take full advantage of mobile phones, allowing callers to send photos, videos, and texting. NG911 will also give dispatchers access to medical data and building plans and traffic alert systems. That's the idea anyways. We are very very far from getting there. Just the first step—getting states to try some calls over an IP network—has been slow going.

Given the ways we communicate today, it does seem bizarre that the only way to report an emergency is still through a voice call. Of course, we want any 911 system to be reliable and rigorously tested, but our emergency infrastructure has consistently lagged behind the rollout of technology. How ironic that the same phones that are so good at helping us navigate our daily lives can become so unhelpful in a live-or-death emergency. [IEEE Spectrum]

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