Roger Anderson is fed up with telemarketers. Rather than just hanging up when they call, he decided to fight back with The Jolly Roger Telephone Company.
Using a system that automatically responds with his voice recordings, he wastes cold callers' time by engaging with them, and then stringing them along so they're less likely to call you.
Here in New Zealand, you can sign up to a Do Not Call registry operated by the Marketing Association. It's not a guarantee that you won't get some nuisance calls, but it should at least reduce the number you're getting. You can find more details and advice at Consumer.org.nz