Definition of "on-hook" [on-hook]

• Describing the state of a telephone (or similar device) when it is available but not in use (adjective)
• Describing the idle state of a subscriber or PBX user loop (adjective)

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• "You may wonder then, why, if the other end (the CALLED end) is still on-hook, there is no 2600Hz coming the other way on the trunk, when there should be."
• "Remember that when you seize a trunk, 2600Hz is indeed coming the other way on the trunk because the CALLED end is still on-hook, but you don't actually hear it because of a filter."
• "The presence of the 2600Hz is telling the billing equipment that your call has not yet been completed (i.e., the CALLED end is still on-hook)."