I was curious to know why I got calls from disconnected phone numbers so I called the phone company and AT&T says that scammers "buy" lists of unused phone numbers to use as their call back number so people will recognize a legitimate phone number and pick up the call. These numbers can be used in two ways, either by an actual phone bank type of caller, or by a computer that just calls all known phone numbers in an area and keeps a record of those numbers that picked up the call. That's why there is no one there when you pick up. The list of "active" numbers (those that picked up) then goes to a phone bank that makes the actual scam call. Supposedly, this process means that the live callers aren't wasting time calling inactive phone numbers! AT&T says there is nothing they can do about it, but if you have caller ID and there is no name or you don't recognize the phone number then don't pick it up. There are some screening machines you can buy on Amazon that will reject incoming calls from unwanted callers, phone numbers, or unknown callers. The machines are a one time expense and start at around $30, AT&T has similar options at additional monthly fees.