They are from places like India the caller ID is made to look like its from the US. Any doubts a guy actually spoke with a guy from India and admitted he's hired to do this. The one he spoke to was trying to say he was in trouble with the IRS. I've received that call twice.
I no longer answer these calls. I search the number like now, then I go back to my phones recent call click info then click block caller.
"They hang up when my machine kicks in with 'Hi, scam calls will be reported...'" They hang up because the machine picks up not because of that message. Computers dial the numbers and if a real person doesn't answer they move on to the next call.