You feel safe having that cellphone with you. If there's ever an emergency—no matter where you are—you can call 911 for help.
Unfortunately, that sense of security is partly an illusion.
Your wireless device has a big limitation: It doesn't give the 911 operator your exact location. So if you can't talk—which is often the case in a medical emergency or a crime in progress—it may be difficult or impossible for emergency responders to find you in time.
"It's a public safety hazard that is largely unrecognized," said Jamie Barnett, director of the Find Me 911 Coalition. "People's lives are at risk right now because they cannot count on 911 being able to find them when they call from a cell phone."
On TV crime dramas, when the good guys want to find someone, they simply go to their computers and instantly locate that person via their cellphone signal. In real life, it's not quite so easy.
If you're outdoors, and your phone's GPS chip can connect with satellites above or the phone hits a series of cell towers on the ground, the 911 operator will know your latitude and longitude—within 50 meters or so—most of the time.
But make that emergency call from inside a building—where it's hard for your phone to "see" the satellites and cell signals tend to bounce around a lot—and your location information could be off by 100 meters or more.
"We have to do better," said Todd Piett, chief product officer with Rave Mobile Safety. "In most cities, just a few meters can mean the difference between several buildings and that can be the difference between life and death."
And then there are those unfortunate situations where the location information turns out to be way off.