Portabella,
Remember all those geometry lessons you hated in school? Figuring out the degrees of the angles in triangles? Thankfully, some geeks love that math and have used it as the basis for telecommunications science. Telecomm technicians/engineers use those same principles to triangulate the approximate point of actual ping locations between towers. Not a perfect science, but it's become far more accurate these days.
In this instance, results may also be supported by GPS information from the iPhone 4s, too. Aside from the standard GPS that Kelli may have had set to active on the phone, many, many phone apps include a service called 'location' on by default. An example: Say Kelli used Facebook or twitter apps on her phone, and had either set to 'update location'. Each time that Kelli sent an update (post), the content would automagically be updated with her GPS location at the time.
Not saying that Kelli did use any app like that the night she went missing, those are just examples of phone apps that usually have 'location' turned on by default.
Police may have:
- The triangulated ping report from teleco
- GPS - basic service from the phone
- Potentially other location updates from app Kelli used on her phone
- iPhone 'find my phone' locater - last set of data
Even with all of those data points, or just one, it doesn't answer where Kelli is, but points LE to where to begin looking for the phone when it was disabled. Kelli may or may not have been near at the time, but whoever was in possession of her phone was last near that ping location, KWIM?
>skip this part if you really don't want a lesson< ;p
(FWIW, all of these application services are all part of big business for software developers these days. They all fall under 'geolocation'. Many companies pay big money, and make big money by gathering data on where people are at any given time. Have you heard of FourSquare or Groupon? People 'check-in' electronically to their local coffee shop, and the local coffee shop uses that knowledge of the customer's proximity to offer coupons, discounts & specials. And they gather a truckload of data about consumer buying habits in the process. All because these cool little gadgets on our phones do it automagically.)
