I have received several calls from this number for the past week or so.
I did not answer the calls, and they did not leave a message.
When I called the number back I too get a recording that says "please leave a mesage after the tone".
I left a message telling them to stop calling me because I do not want calls from them, and that other people getting calls from them feel the same way. I did not leave my number. They are obviously not legitimate, so I do not want them identifying me.
If I keep getting calls, I will consider a complaint to the California Public Utilities Commission.