A call from this Santa Monica landline arrived today.  When the call rolled to voice mail, the caller left no message.  This behavior is typical of robocallers, who use automated dialers to place calls.  If a live person answers, the dialer transfers the call to a live telemarketer.  Neat, huh?  Since I neither anyone nor do business with anyone from Santa Monica, I must presume the robocaller is a Do Not Call law violator -- i.e. an illegal telemarketer.

Exactly as you described.  CID on Ooma said J S Signet.  Don't know em, don't wanna know.  No message left.  Blocked now.