0-9 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
1. In telephony, the condition that exists when an operational telephone, or other user instrument, is not in use. (188) Note: On-hook originally referred to the storage of an idle telephone receiver, i.e., separate earpiece, on a hook that extended from a vertical post that supported the microphone also. The hook was mechanically connected to a switch that automatically disconnected the idle telephone from the network. 2. One of two possible signaling states, such as tone or no tone, or ground connection versus battery connection. (188) Note: If on-hook pertains to one state, off-hook pertains to the other. 3. The idle state, i.e. , open loop, of a subscriber or PBX user loop. (188) 4. An operating state of a communications link in which data transmission is disabled and a high-impedance, i.e., open circuit, is presented to the link by the end instrument(s). Note: During the on-hook condition, the link is responsive to ringing signals.