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
As a safe bet: Almost everything “advanced tech” on tv is unrealistic.
The tech is there to drive a fictional narrative. Not to document the historical setting. Things only need to resemble reality. Inspiration from old tech helps this realistic feeling.
I also assume there might be laws that restrict the details movie makers can show in context of law enforcement operations and government spying.
Enhance!