Only way to stop all this is by getting caller ID and answering machine. NEVER pick up phone if you don't recognize the number. Legitimate callers will leave a message. If no one answers their phones, the crooks and scammers will soon have to give up this apparently lucrative "business."
they're back! Called me back in 2014 and they are starting up again! Caller id "Venice FL". Left no message. Believe it to be a scam energy audit trying to get you to buy their "energy saving" products.
Get yourself an answering machine to screen your calls. If you do not recognize an incoming call, let it slide to your answering machine. If you then recognize the caller's voice, you can pick up; otherwise, just ignore the call and absolutely do not return any call you do not recognize. That is what I do. Good luck.