I’ve written about e911 before, most recently in July where the concept revolved around the role of media servers with e911 and NG911 services.
I was recently doing some more research on e911 when I came across this interesting paper on the GSA site about location-based services and the accuracy of them. You’ll need to register to read the entire paper but if you are into math, non-linear equations, and azimuthal alignment of antenna arrays, it will be worth it. As 911 evolved from a landline based system to one where 911 callers were calling from mobile devices, it became important to try and use location-based services to pinpoint where the caller was calling from. With landline based services, the phone number is from a fixed location so the location of the caller is known.
At any rate, this paper goes into why there are potential inaccuracies with using location-based technology (and how a test solution measuring antenna location, azimuth, tilt and roll helps resolve the issues). And if you think that your phone has a GPS in it, it probably does if it’s a smartphone. But still a vast majority of the phones out there are not smartphones, so accurate location-based technology is still important.