Thanks, I haven't read the link yet so maybe this is answered but one thing I don't know the answer to is what cause a phone to ping.
Does there have to be some kind of attempt to communicate with it or will it simply send out an "I'm here" signal everytime is passes a mast/cell tower?
I'm confused about whether the pings from Christina's phone mean that someone was trying to contact her at those times or whether they are just routine things and only a selected few of the many more that LE know about.
We don't know what information they are using, but a ping indicates the phone is communicating with the network tower to locate it. I believe they could get this info from an actual text or call to the phone, too.
Just wanted to reiterate and reinforce this concept. Cellphones that have a power source are pinging cellphone towers all the time. The network needs to know where your phone is, so an incoming call can be directed to you, and you'll have connectivity and be able to place outgoing calls when you push the send button. So pings are happening every few minutes, wether you're using the phone or not. This is what will eventually drain the battery of a phone if it's not charged, even if it's not used.
In the Casey Anthony case, I recall that there were hours upon hours, days after days, when Casey was at home, that her cell phone pings bounced back and forth between two roughly equidistant towers. After a while, sleuther's came to recognize that those times periods on the phone records when those two towers were "ping-ponging" it meant Casey was at home.
So, to answer SuzyJackson's question, the phone will ping even when it's not used. Pings will alternate between multiple towers, even when I phone is stationary, because the tower service area overlaps to allow continuity of service as a phone customer is moving, that way there aren't breaks in the call when you're switching towers (well, theoretically - we all know cell calls sometimes get dropped; it's usually at a tower hand-off).
Pings are not something that shows up on a regular phone bill, but something LE would have to access. It's not clear that citizens can get this information, but I found a good read from PursuitMag about "
Locating Mobile Phones Through Pinging and Triangulation" in a popular article written in 2008, and updated in 2012.
There's also a good New Yorker article, "
What Your Cellphone Can't Tell The Police" piece that discusses how LE may over estimate the specificity with which a Ping can tell us where a person is. A woman was wrongly convicted based on ping evidence and eventually exonerated.
