blue box

n.

1. obs. Once upon a time, before all-digital switches made it possible for the phone companies to move them out of band, one could actually hear the switching tones used to route long-distance calls. Early {phreaker}s built devices called blue boxes that could reproduce these tones, which could be used to commandeer portions of the phone network. (This was not as hard as it may sound; one early phreak acquired the sobriquet "Captain Crunch" after he proved that he could generate switching tones with a plastic whistle pulled out of a box of Captain Crunch cereal!) There were other colors of box with more specialized phreaking uses; red boxes, black boxes, silver boxes, etc. There were boxes of other colors as well, but the blue box was the original and archetype.
2. n. An {IBM} machine, especially a large (non-PC) one.

---