This person calls my worksite weekly.  They hold the phone line never utters a word not hang up.  I refuse to call them back just in case it's setup to bill your phoneline?  It's very annoying and it's not your typical sales call.  I strongly wonder is this person an stalker?  I don't feel good about it and with todays cellphones?  Although the area code is 559 far away? It doesn't mean he isn't standing outside your doorway.  Just be care and check out your environment often.