I also am getting calls from this number (440-210-4370).  Caller ID shows NUFIC but they leave no message. If you call the number back and listen to the recording you add your number to the do not call list.

Numerous calls were received over the past couple of weeks from this number. They never leave a message. After some personal investigation I discovered the call is from a cell phone in Painesville, Ohio, of which Level 3 Communications is the carrier. This number (440-210-4370) seems to show up on many scam complaint sites also. Some suggest it's an insurance company - NUFIC - but I could not determine anything positive to confirm it.