Caller calls, but when I answer it, they hang up!

Silence at first then a woman comes on asking for a "Gabriel". No Gabriel in my household. Calls every day at different times. Today I answered the phone and said "hello" 3-4 times and they hung up. Who the hell are these people???

don't know who this is

Computer voice said that I won 2.000 Airmiles and to press #1, then heard 'hold Music' and then they hung up.

Told me that they can help settle a debt and wanted my information. Told them that it wasn't there business. And they said it was. Informed me I owed a debt and if I didn't pay they would send the police. I told them go ahead I'll be waiting with the coffee and donuts. Haven't heard from them since. If you pick up and get a live person call their bluff.