You can do this at home, but not at work. I usually let these scam phone calls just ring and let the answering machine kick in, but after a while, it's the same # calling and calling and calling. What I do now, is I keep a police whistle by the phone, and when these calls come in, I blast the whistle for about 5 seconds. If it's not a "robo-call", but a live person with a headset, this will really piss them off and hopefully stop the calls...
called and left no VM. Called back and they want to give you $100 in gift cards, but hang up when you ask what company they are from. NJ caller ID, but phone worker sounded foreign.