My number is on the DoNotCall list ... and I got a call from this number, it showed as from Sunnyvale CA ... I didn't answer the call. They left no message. I recall answering another call from an unsolicited robot call energy bill scammer prior to this ( I hung up then). This number is blocked now. There maybe another related number (415) 366-0718 shown as from Belvedere, CA ... both are blocked now. I'm sure there are others.
They called and left no message. I called back and got the message "all our agents are busy. We will call you back tomorrow".
Added the number to my blocked list