No msg....SOB's

Received call from this number. Looks like as spam.

Caller ID shows, 'local call area', didn't ans.

These people call and do not leave msg.

This same voice keeps calling my house, I keep blocking the number and they call back from another number, all they say is "Is Joseph there?" several times on my answering machine, they never say who they are or why they are calling. We are on the do not call list but we continue to get constant annoying phone calls, what's the point?
I called the number back to tell them to stop calling me and I got their voice mail. The voice says "hello" twice and then says that they cannot come to the phone. Definitely some type of scam