That particular way of annoying people that consists of employing small groups of other people to sit around in call centers for hours calling larger groups at random - usually during dinnertime or weekend mornings when you absolutely don't want to be interrupted.

In the old days, it would have been considered too cruel to be called anything other than psychological warfare. Now, it's just another sales tack.

Since tele-marketers usually follow scripted prompts, here's a local copy of a counterscript for my own behalf (also available as a PDF).