h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

In the US there is a law (the Telephone Consumer Protection Act, or TCPA) that states that telemarketers must fully identify themselves, restrict calls to the hours between 8 a.m. and 9 p.m., record and respect do-not-call requests, and refrain from calling with a prerecorded message.

In order to be put on a do-not-call list you can tell each telemarketer "I wish to be placed on your do not call list". There are several listing services that advertise that they will put you on "master" do not call list for a fee.

Many local telephone service providers also offer a service that guesses* whether a caller is a telemarketer, and if so will play a recording stating that the owner of the called number does not wish to receive telemarketing calls, please place them on your do-not-call list, etc. If the caller still wants to get through thet must hit a key on the phone (usually # or *) to get through.

However, in order to receive the aforementioned service one must already subscribe to caller ID. The anti-telemarketer service then costs an additional fee, in addition to caller ID fees.


*The phone company searches for the caller number. Most call centers block their caller number, so anyone calling from a blocked caller number is assumed to be a telemarketer. This can be troublesome if a caller is calling from a pay phone or call center.

Useful sources:
[URL's removed by moderator]