A blue box is an electronic device that produces tones used to generate the in-band signaling tones formerly used within the North American long-distance telephone network to send line status and called number information over voice circuits. During that period, charges associated with long-distance calling were commonplace and could be significant, depending on the time, duration and destination of the call. A blue box device allowed for circumventing these charges by enabling an illicit user, referred to as a "phreaker," to place long-distance calls, without using the network's user facilities, that would be billed to another number or dismissed entirely by the telecom company's billing system as an incomplete call. A number of similar "color boxes" were also created to control other aspects of the phone network.
a blue box is an electronic device that produces tones used to generate the in-band signaling tones formerly used within the north american long-distance telephone network to send line status and called number information over voice circuits during that period charges associated with long-distance calling were commonplace and could be significant depending on the time duration and destination of the call a blue box device allowed for circumventing these charges by enabling an illicit user referred to as a "phreaker" to place long-distance calls without using the network's user facilities that would be billed to another number or dismissed entirely by the telecom company's billing system as an incomplete call a number of similar "color boxes" were also created to control other aspects of the phone network