Years ago calling and immediately hanging up was immensely popular among teenagers/young adults as a way to ping someone. Used as a way of flirting, telling something was ready, arrived at home.
Calling and hanging up didn’t count, so that is what we would do. We would know to call back.
Years later I ran reports for call centers. I would run data every which way.
Found an agent that would dial a disconnect number hundreds of times a day.
Went to big boss, as I couldn’t figure out the rational.
He took one look at it, and cursed “well know we know how he has top numbers.
Found so many ways agents would mess with metrics