Definitions for "On-Hook"
Keywords:  cradle, handset, idle, hook, telephone
When the telephone handset or receiver is on the cradle; the circuit is open (inactive) and cannot communicate information.
Station switchhook contacts open or whatever supervision condition is indicative of the equipment-idle state.
The active state of a customer telephone circuit. The term is derived from old telephone sets where the receiver, when not in use, was placed on a hook attached to a switch. The opposite condition is off-hook.