Spam.Spam.Spam.Spam.Spam...........

I've been getting a LOT of calls lately from spammers, including this one.  No message. Just keep on calling...
also, area: "unknown"??

The phone rings once and then they hang up. Annoying

This is one of several calls I have been getting since 3/31.  No message. I want it to stop!!

I have no idea who this is.  The call originates from California.  They call  often and leave no message.  Usually, they ring twice and then hang up.  I'd love for them to stop calling.  However, I am afraid to answer the phone.  I don't need any nonsense from some sort of spammer...