Does anyone have any good, referenced based info on cell phone use in rescues?

Cell phone "pings" gets a lot of attention.

For example, on a recent SAR mission, the missing person had a Verizon phone with the E911 chip. Our searchers found the missing subjects within 50 yards of their reported position.

I have heard mixed reviews about cell phone tower triangulation. Where I live in Central Oregon, there may be only one tower to get any data and that info can be miles off.

Thanks in advance.

Blake
www.outdoorquest.biz