Got two calls in two days from this #, after double blocking (external & internal) 000-000-0000. Never, never, NEVER answer these calls- they are criminal scammers. Blocked 727-000-0000, and will see what happens.
Weirdly enough, my VOIP software identifies this caller as "O" (the letter, not the number). Apparently, some scammers are now using different software to block/disguise their real identity/number, thus showing up as all zeros, or other odd combinations. Kind of defeats their purpose in trying to deceive people...

Caller ID read 'Unknown'. Some man sitting behind computer using autodialer wanting to ask two questions on who I had voted for. When I declined to answer, he told me I should not have listed my number when I registered to vote.