On-hook - AbsoluteAstronomy.com

Telephony

In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....

, the term on-hook has the following meanings:

The condition that exists when a telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...

or other user
User (telecommunications)
In telecommunications, a user is a person, organization, or other entity that employs the services provided by a telecommunication system, or by an information processing system, for transfer of information....

instrument is not in use, i.e., when idle waiting for a call. Note: on-hook originally referred to the storage of an idle telephone receiver, i.e., separate earpiece, on a switchhook. The weight of the receiver depresses the spring-loaded switchhook
Telephone hook
A telephone hook or switchhook is the cradle where a telephone handset resides. It takes its name from old wooden wall telephones and candlestick telephones, where the mouthpiece to be mounted on the telephone box and, due to sidetone considerations, the receiver was separate, on a cable...

thereby disconnecting the idle instrument (except its bell) from the telephone line
Telephone line
A telephone line or telephone circuit is a single-user circuit on a telephone communication system...

.
One of two possible signaling states, such as tone or no tone, or ground
Ground (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....

connection
Electrical connection
An electrical connection between discrete points allows the flow of electrons . A pair of connections is needed for a circuit.Between points with a low voltage difference, direct current can be controlled by a switch...

versus battery connection. Note: if on-hook pertains to one state, off-hook
Off-hook
In telephony, the term off-hook has the following meanings:# The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating. Note: off-hook originally referred to the condition that prevailed when telephones had a separate earpiece , which hung...

pertains to the other.
The idle state, i.e., an open loop of a subscriber line or PBX user loop.
An operating state of a telecommunication circuit
Telecommunication circuit
A telecommunication circuit is any line, conductor, or other conduit by which information is transmitted.A dedicated circuit, private circuit, or leased line is a line that is dedicated to only one use...

in which transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...

is disabled and a high impedance
Electrical impedance
Electrical impedance, or simply impedance, is the measure of the opposition that an electrical circuit presents to the passage of a current when a voltage is applied. In quantitative terms, it is the complex ratio of the voltage to the current in an alternating current circuit...

, or "open circuit
Electronic circuit
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow...

", is presented to the link by the end instrument
End instrument
In telecommunications an end instrument is an equipment connected to the wires at the end of a telecommunications link. In most cases, this is a telephone. End instruments that relate to DTE include Printers, Computers, barcode readers, Automated Teller Machines and the console ports of routers....

(s). Note: during the on-hook condition, the link is responsive to ringing signals.

The act of going on-hook is also referred to as releasing the line or channel, and may initiate the process of clearing

Clearing (telecommunications)

Clearing, in telecommunications means:* A sequence of events used to disconnect a call and return to the ready state. It is sometimes, particularly in the context of common channel signaling, called teardown....

.
See also disconnect supervision

Disconnect supervision

Disconnect supervision is a term in telephony describing signaling between the telephone exchange and a connected party used to indicate that the connected call is being disconnected....

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.