How about CAPTCHA for unknown calls - numbers not in your contact list will be required to answer something only a human is capable of answering before getting through to you.
Or another approach that Google does with Google Voice is to ask the caller to identify before the call goes through. Then the phone rings on your side and you hear the name of the caller before you decide to answer.
I'm working with a friend to build this. You can sign up to beta test at https://quitcalling.us. You can also text a telemarketer's number to 865.407.2730 and our system will file a complaint with the FTC on your behalf.
This is only effective against the relatively honest telemarketers that use correct Caller ID information. The really bad ones, like the one involved in this article, use spoofed Caller ID -- reporting them to the FTC is a waste of time for everyone involved.
It wouldn't be if anyone actually followed through on the complaint. Each company knows who sent them the call, even if the caller ID is misleading. (Though you might have to keep digging though several companies to find the actual call sender.)
I have a something like this that I setup via Anveo.
Whitelisted numbers ring my line. Blacklisted numbers are hung up immediately. Everyone else gets a message saying "Press 1 to be connected." If they don't, they go to voicemail.
Or another approach that Google does with Google Voice is to ask the caller to identify before the call goes through. Then the phone rings on your side and you hear the name of the caller before you decide to answer.