We have caller ID so I don't answer if I don't recognize the number.  When the answering machine comes on they hang up.  It sounds like a real person not a robocall.

Calls and hangs up.....

This number keeps calling and hanging up on me.  When I try to call it back it is either busy or says call can not be completed.

Man calling and wanting me to sign up for cheaper natural gas prices, but to continue using my present gas company which is Nipsco. I told him no and that I never do business over the phone. I told him that I had no idea who he was.