I use 'Phone Tray Free' from (
http://www.phonetray.com/ ) to identify (and potentially block) all the phone calls I get. I am in LOVE with the program and its free. Apparently there is a pay version which I know nothing about.
The catch(es)?
You have to have caller ID coming in.
You have to have a (windows?) computer with a modem
Have the above two plugged into each other as well as both turned on
Now you can set the tiny program to handle all calls with "varying" messages by caller, or area code. I use the disconnected message for 800 numbers and "Does NOT accept Private/anonymous calls" for that type. There is even a fun one to torment your friends. ie monthy python, "you shall not pass". If I'm not mistaken, you can add your own. The best part is the tones that some of the messages have before the message( (do Do DO) "We are sorry. the number you called is not ....."). These tones actually tell the computers that your number is disconnected or no longer in service. .... and you don't even have to ask/tell/yell at anyone to do this. Its automatic once you tell the proggy how you want "this" number handeled. A person of course will stop calling when they get this as well eh?