They can input into software whatever number they wish to show

It's called spoofing and is probably illegal, but, since, in my case, it's collections people, they don't care; they would rather take the chance that their company will get fined and that they, by getting you to pick up, might get the call recipient to pay a delinquent debt, and, thereby, collect a commission, for themselves

It's stupid, but they are bored, so they put in a number they think is cute

who is this calling i want to be left alone