So why does 911 sometimes have more difficulty finding callers than, say, Uber? For decades, wireless providers have relied upon information from phones pinging cellular towers and from GPS to provide location estimates for 911 systems. You'd think that would work pretty well. But Evelyn Bailey, executive director of the National Association of State 911 Administrators and former head of Vermont's first enhanced 911 system, explains that those methods aren't always so reliable.
"It depends upon the infrastructure that's available where the caller is located," she says. If you're outdoors in a place where you're close to a cell tower and the GPS signal isn't obstructed, you're probably OK. But if you're out in the mountains where cell coverage is spotty, or inside a building with lots of metal in it in a densely developed urban area, it could be a lot tougher, she says.
Your phone, though, has other ways to locate you. Thanks to technological advances by mobile phone manufacturers, your device can use your proximity to Wi-Fi networks and Bluetooth beacons, and even readings from the barometer that you didn't realize was built into your phone, according to Trey Forgety, director of government affairs and information security for the National Emergency Number Association, whose 12,000 members include staffers at emergency call centers and emergency system technology companies. That data comes from what Forgety calls the "user plane," and historically, wireless carriers haven't trusted it as a location source to fulfill their regulatory obligations, he says.
But even if they did, Bailey notes that existing 911 systems aren't engineered in a way that makes it easy for them to accept that data into their "location stream."