From the Chatham Star-Tribune....
'Investigators reportedly used geo-location to triangulate a cell phone involved in this case, and it pinged for 20 minutes around the local resident's property.'
My understanding of the technology is that there was not necessarily a 20-minute phone call. Many things could make the phone ping, I believe...including making or receiving a text message, any notifications, email program checking for updates, which normally may occur every 5 -15 minutes, any app data being received, etc. JMO