How do trap-call work?

A trap call works by allowing a user to identify the phone number of a caller who is blocking their caller ID. When the user receives a call from a blocked number, they can press a designated key combination (often *57 or similar) after the call ends. This action triggers the phone company to trace the call and retrieve the caller's number, which is then typically sent to law enforcement or provided to the user. It's important to note that the effectiveness of trap calls can vary by phone service provider and local regulations regarding privacy.