United States, couple years ago my friend in his mid-thirties was feeling depressed after his mom died. Came over to hang out, and wasn’t responding to his sisters calls. His sister called in a welfare check on him and suddenly I have three cops knocking at my front door. They ask for him by name, say he isn’t in trouble. I go get him; he asks “how did you know where I was?” and the cops say “we pinged your phone”. W…
Triangulation by cell tower is really, really accurate.
Looking at call logs may require less.