HOW I HANDLE INCOMING CALLS: My phone at home goes directly to an answering machine so I can screen calls, if I'm in the house. Family, friends, business associates, and neighbors were told of this fact, and therefore will begin their message. Those who do not wait the 5-7 seconds to start a reply are probably scammers or politicians (or both). To avoid the constant disruptive noise, I disconnected the telephone ringers -- no more ringing "dozens of times" every night and day!
We got a call this A.M (FYI: we're in AZ) and the person on the other end forgot to hang up so I was able to hear him talking with another person. It appeared they were going over their spiel or sales pitch. Unfortunately, who ever they were, they did not have a good command of the English language and whatever they were trying to say made little sense. It appears they may have known my wife was a retired teacher from some of the conversation I could make out. That's a little scary...
You can zig and zag and go through contortions trying to avoid these scum who violate the National Do-Not-Call Registry, but they will always find ways around... My solution is to make their business model impossible to maintain. With these CC-reduction folks, I have some bogus numbers/exp date written down on a card. When they call, I S L O W L Y express interest, then S L O W L Y read the numbers when requested. When the card comes back invalid, i read it again, this time changing a number (like a 3 to an 8 - easy mistake...). Repeat until you sense they are getting antsy. The object is to keep them on the line as long as possible, wasting their time. Maybe more importantly, ultimately they will become sensitized to the possibility of being punked, then start hanging up on actual potential customers. Bonus points if you can get in a mention of the NDNCR before they hang up...