Some very clever people who were annoyed with telemarketers decided to create some computer code to annoy them back. Telemarketers use technology to increase their productivirty. These clever people decided to use the same technology to lower the productivity of telemarketers. It is kind of like a honeypot on a network to slow down hackers.
The software works with caller-id and a list of annoying telemarketers that you provide. When one of the telemarketers calls, it answers on the first ring. Your computer will then begin by playing the first of a series of prerecorded audio files. It then waits to hear noise on the line. When the line goes silent once again, your computer will then play the next prerecorded audio file.
An added bonus is that the software records the calls so that you can hear them later. This makes for some funny recordings. The software is also free and open source.
I am lucky in that my number is unlisted, and I do not receive many telemarketing calls. I know of others that get them all the time. They would welcome something like this.
Read all about it on the Telecrapper 2000 page.