After learning how to create my own spam filter via a combination of procmail and SpamAssassin I've started wishing I could 'procmail' my phone line. Also apply some of the thinking of the better spam filters to my phone line. :)
Since I operate on a cellphone, it would work like this:
a small fee, my phone company provides me with a website I can log into where I can screen incoming phone calls to my line.
The site has several options:
Option 1: All phone numbers that come up as "unavailable" on your Caller ID routes the number directly to your voice mail without ringing your phone. Comes with "fake extension number filter" (see below) turned on by default.
Option 2: Detects a particular number from a person you really don't want to talk to - such as a nosy in-law - and also routes that number to voice mail without the phone ringing. Comes with "fake extension number filter" (see below) turned OFF by default.
Option 3: Forwards the call to the phone number of a known telemarketer (or annoying human being of your choice).
Option 4: Routes the call to a recording of a busy signal. Good for that one yappy phone-hog you'd rather not speak to at all. Also good for convincing the boss you ARE really sick (that's your story and you are sticking to it) as well as talking at home on the phone all day.
Option 5: Routes the call to a "this number is not in service" recording. Good in an emergency situation for avoiding evil stalker types.
TELEMARKETER'S PHONE NUMBER CAPTURE SERVICE
OK, despite your best efforts, some annoying telemarketer has managed to get thru your phone filter by using a legit-looking number on your caller ID. Easy fix! Easy revenge! Instantly press star-something to add this annoying telemarker's number to a "Telemarketer Numbers To Ban List". Not only is that telemarketer's number added to your own personal phone filter, but it is also added to the phone filters of others who also subscribe to the service. You can then add it to your option 3, above.
FAKE EXTENSION NUMBER FILTER:
The problem with some normal "privacy manager" phone schemes is that there are some good reasons for certain folks to screen their numbers. Doctors calling back their patients from their private numbers (can't get to the office at that time) have real problems with this scheme. If the doctor followed normal "privacy manager" procedures to have their number unblocked to their patient's caller ID, not only is the doctor opening up his own personal number for abuse, the patient may innappropriately try to call that home number instead of the more appropriate clinic number in an emergency. This, as I understand, is a real PIA to medical professionals, especially to psychiatric professionals who don't need unbalanced patients accessing their private numbers (no kidding!!).
The answer to this is the "Fake Extension Number Filter". Everyone pretty much understands what an extension is (duh). Ya dial the phone number, wait for the proper prompt, type in extension, and you usually reach your party.
When you give your number out, also include the fake extension. When someone's calls who has their phone number coded as "unavailable", the phone prompts an extention number prompt, they type it in and your phone happily rings. If no extention is entered, the phone automatically goes to voice mail without a single ring to your phone. :)