I keep getting calls from this number and once they left a message saying "This is National Home Protection...are you there?" And that is it. It sounded like a real human, but it is most likely pre-recorded.
They called me yesterday and when I picked up the phone, the guy told me he is "Tom with home protection". I immediately hung up as they are well-known scammers (google "Tom with home protection").
I don't answer calls from numbers I don't recognize. As these calls are received, I Google to make sure they are reported by others and save them with the name "spam" and set the ring to NO RING. That way I don't hear it if they keep calling back, only the beep that I missed a call.