Blue box

An early phreaking tool, the blue box is an electronic device that simulates a telephone operator's dialing console. It functions by replicating the tones used to switch long-distance calls and using them to route the user's own call, bypassing the normal switching mechanism. The most typical use of a blue box was to get free telephone calls. Blue boxes no longer work in most western nations, as the switching system is now digital and no longer uses inband signaling. Instead, signaling occurs on an out-of-band channel which cannot be accessed from the line you are using (called Common Channel Interoffice Signaling (CCIS)).

Related Topics:
Phreaking - Electronic device - Switching system - Common Channel Interoffice Signaling

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