Phoned at 7:55 PM. No message left.
800notes has lots of posts regarding a very similar number (415-991-7603) which also started recently. (Oct 15)
My suspicion is both numbers are being used by the same party. Probably a scam. I don't answer unrecognized numbers.
robo call saying i won the lottery and should call to claim it (i don't buy lottery tickets). filed a complaint to FTC (DNC). everyone, please do the same.