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 phreakers 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. 2. n.
An IBM machine, especially a large
(non-PC) one.