Phreaking is making calls without paying for them. Phreaking can be done in several ways. There are many Colored Boxes, which all do something else. The Blue Box was the first one, invented by Al Gilbertson. The Blue Box gives you control over the phone system like an operator. There are many, many more Colored Boxes, and I will describe some of them.
But, there are more ways to phreak. An electric organ for example can emulate the tones used by the phone system. The very first phreak did it another way: Joe Engressia used his voice.
Phreaking is more than only making free calls. Phreaking is just like hacking: pass through security systems, explore the frontiers of the system. Go where nobody ever went. And getting a kick of it.
One of the most legendary phreaks was Captain Crunch, named after the Cap'n Crunch cereal breakfast. The makers of this packed a small toy with it, which used to produce a perfect 2600 Hz tone. He drove around the USA in a Volkswagen van with and entire switchbord and a tonegenerator in the back. He stopped at a telephone near a lonely highway and sat there, making calls zipping through the world, for hours, for days sometimes.
Well, this article isn't about phreaks, but about their methods, the phone system, and how phreaking became posible.