Today they called as "Private Caller."
I felt like growling at someone so I answered the phone.
"Is the lady of the house there."
"There IS no lady of the house, just like all the other times you've called."
"We're ..."
That's when I hung up on them.
If you really want these calls to stop then STOP ANSWERING WHEN THEY CALL!
A lot of these calls are to test different times of the day to see when someone will answer. Then they sell your number along with the times someone has answered. Expect more calls during that time. This is why they sometimes call several times a day. I quit answering calls from unknown numbers. It took a while and I now hardly ever have one of these calls bother me.
Remember, you have an answering machine or voice mail. If you are unsure simply let the call go there then listen when they hang up. You will know if it is important and also be on the path to ending these annoying calls to your number.
Most of the time they either do not leave a message or their message is under 10 seconds.