I have been putting my phone on fax mode so these morons will give up.  It's annoying to those who really need to reach me but hope this method will register to the telemarketers and scammers that they won't get through.  For all the rest the caller ID s that are known to me I ll call back and apologize for the fax tone.  My theory is to get rid of them, not just to block the ring tone.