Here's the answer to all our prayers.  I found this on a site I posted a telemarketer's number at.  I tried it and it WORKS!  I put the tones at the beginning of my phone  greeting about three months ago and in the last three weeks have had "ZERO" calls.  Whover posted that "THANK YOU, THANKI YOU".   Here's what I found:

Telemarketers almost exclusively use autodialers to make their calls.  One out of a thousand will have live reps doing the dialing.  When these dialers connect (you  answer the phone) they first listen for any tones generated.  If no tones are detected they then transfer the call to one of the reps in a call center.  If the autodialer  hears the 3 beeps from dialing a "DISCONNECTED" number, the number that was just dialed is automatically "REMOVED" from their list.  Below is a link that has  this tone plus the verbal message.  You DO NOT need the verbal message.  Download or copy the "DISCONNECTED" MP3 or WAV file to your desktop.  Create or  change the greeting you have when someone calls you and you're not available.  At the VERY BEGINNING of your message place the 3 tones (NOT THE VOICE  MESSAGE) then continue with your usual or normal greeting.  The autodialer will hear the tones and BINGO, your number will be removed since they think it's a  disconnected number.  DONE.  In a few weeks you will be removed from all or most of the lists.  Of course you may have to explain the tones to the callers you DO  want to speak to but that's a small tradeoff.  Pass this info on to anyone you know that gets junk calls or even help post this on these websites.  If you continue  getting calls after reading this, it's your "OWN" fault!  END JUNK CALLS.  

http://www.payphone-directory.org/sounds.html