if you listen to the police scanner,, you will hear them looking for people,or vehicles, and one tool the police use is the cell phone, and the trianulation.
a b/f threatened the g/f... then took off.. police are looking to talk to him,, they get the dispatch to PING the phone ... the towers report it is within 3m of 123main st , toronto on.
I have heard this request many times,,, recently,, the police knew the suspect was in a back yard of a certain address, by his cell ... and they got the dog to point him out.. it was funny to listen to the cops when the guy popped out, and started to run!
we had a personal truck stolen from work parking lot... it had a company phone in it... the police PINGed the phone and knew it was 20km south,, so they called that police force to check it out.. who reported it wasn't where it was reported to be... well,, in the 10min delay,, the stolen truck had travelled a few miles... and they pinged it again,, this time,, it was reported to be within 2km of where it was taken from,, and in a parking lot where 2 other trucks were reported about 10 min later.....
one last ping,, put the truck 20km away again... and then the phone was turned off,, or went dead.
later, they found all three trucks very close to the last ping location,, being dismantled .....
I have heard them ping phones for .. stolen vehicles,, to locate attempt suicide people, to check well being,, and others... and it doesn't take them long to go thru the process..
I can only assume the process, police interview family or friends, or anyone that might have suspects number , aquire cell no., give it to dispatch, who checks provider.. and then calls bell, or telus, or whoevers tower that phone uses.. and requests a ping for location.. then dispatch gives that info back to LEO ...
listen yourself..
http://cykf.net/Liveatc/Police&audio.htm