I solved this issue completely...
No more scams, no more harassment, no more wrong numbers, no more telemarketing.
1) get a Google Voice number or equivalent.
2) set the defaults such that ALL calls go directly to voice mail without ringing any lines.
3) set a generic voice mail greeting indicating something like "Due to excessive marketing and scam calls on this number, all calls to this number are screened by an electronic system. You MUST speak your name and then leave a voice mail to be called back. If no voicemail is left at this number, it will be impossible to have your number added to an approved caller list. If you believe you are receiving this message in error, please contact the owner of this number through another means."
4) add all your family and friends to approved caller lists. Set the default such that the caller name is spoken by Google when they call in case you answer without looking, but have caller ID passed through so you can see without answering. Some specific people you always want to answer from put in separate groups if you don;t want to have to accept the call after answering.
5) Have voicemails forwarded to your e-mail, and if possible change your Google voicemail to be the default voicemail system for your phone (this can be done on iPhones and many others) If you get a voicemail from a name or number you do not recognize, Google the caller's number to ensure they're not scammers calling.
6) on Google voice, go to history. For numbers of people you like, or companies you actually want calling, add them to lists to pass them through to your phones. For each number you want blocked, click the "more options" link near the number and select "block this caller" and they'll never get to your voicemail box again.
I sync my google contacts with my phones, so anyone with approved numbers has a contact on them. I set a ringtone and vibrate option for all of them. My default ringtone for all other numbers is silence (a null ringtone), and I have vibrate set to off. This way if someone calls my cel directly (not google voice), i don't know they are, and ignore them. I have my cell phones set to not use their own local voicemail, but instead forward all calls to my GV number after 4 rings. This way, they show up in my google history even if they don't call my google number. My GV number is the ONLY number I give out for any reason, so over time less and less people and companies are calling my cell. AT&T is also nice enough to offer me an option to do call filtering, so only calls from a few area codes can even ring my cell phone at all (I was getting abusive amounts of texts from non-normal formatted numbers when i got this line, so they added that option to me for free, most people have to pay for it though). 800, 866, etc numbers simply can not call my cell phone (they have to call the GV number).
I went 1 step further... I have a dry line with the phone company for DSL. My home phone is Vonage and we have cells too. The dryline actually HAS a phone number. So, i called the phone company and asked them to do me a favor, and I had them redirect calls from that number to another one. They charged me the call forwarding feature, but no actual line charges. ($3 I think?) I used the web site to set up forwarding for that number to the FCC abuse hotline! Calls i don't want get blocked, but marketers who abuse the do-not-call list, and scams, get redirected RIGHT TO THE FCC!!!! I love it.