This number keeps calling my work number. And my cell.  And I can't hear anything.

This number keeps calling my work number. They first time/few times they call it pops up on my caller ID as an "Unknown Number" followed by more calls at the number 347-927-4859. When I answer, nobody is on the other side, although at times I can hear noises, but never speaking. It keeps calling repeatedly, and does not leave any messages.