I get these calls a couple times a week. It used to be a lot more until I figured out the following. These calls have one thing in common....they hang up before the voice mail kicks in. Why? it costs them money if the call is answered. Two solutions, let them hang up, or answer and don't say anything. Keep them on the line as long as you can. It may cost you five or ten cents (or nothing if you have unlimited minutes) but it costs them, if nothing else, the employee"s compensation and possibly phone charges.
I don't know anyone in CA so I did not answer. When I dialed the number back, a robo voice kept saying "if you want to be placed on a do not call list press 1". I didn't to it. I'm assuming it's a scam of some kind
Called my land line twice within 1 minute, and I didn't pick up. They left no message. Both the number and the name for the caller ID were displayed as 213-213-5992. Since that's obviously spoofed, and Doris received a call from the same number only 4 hours ago, I'm guessing this is a scam.