Who called from 6128232429

When I saw this number I knew it was a number I did not know. When I answered it sounded like no one was on the other line and if I called the number back it would have a disconnected tone.

I received three calls from 612-823-2429 within the last week, but when I answered no one was there and when I called the number there was a disconnected tone.

Same here, multiple calls with no messages left.

I have received several calls per day from this number.  It sounds like someone is there, who will not respond.  How do you stop this?