Trope: Police have to keep bad guy talking on the phone long enough to trace them and find their location. Professional bad guys hang up right before it triangulates their coordinates.
Apparently, Hollywood’s been getting this inspiration from a pre-digital age when they use this trope in movies. See link for more info. It’s just funny that most of the “tracing the call” scenes I’ve seen are definitely after the 2000’s.
Another link: https://slate.com/news-and-politics/2002/10/how-hard-would-it-be-to-trace-the-sniper-s-phone-calls.html
A fun gif: https://i.gifer.com/9QtC.mp4
It goes through your phone’s data connection. That’s part of the reason we don’t get GPS info on all calls, no data, no gps. If you call from a deactivated cell phone that can only call 911 for example, since you don’t have data we don’t get that gps data(or your emergency contact or medical info if you’ve filled that out on your phone)