Editing On- and off-hook (section)

==Off-hook==
[[File:Trimphone, Off Hook.JPG|thumb|  Off hook telephone. ]]
The term '''off-hook''' has the following meanings:
* The condition that exists when a [[telephone]] or other [[User (telecommunications)|user]] instrument is in use, i.e., during [[Dialling (telephony)|dialing]] or communicating.
* A general description of one of two possible [[Signaling (telecommunications)|signaling]] states at an interface between telecommunications systems,<ref>{{cite web
 | url = https://archive.org/stream/bitsavers_westernEleEngineeringandOperationsintheBellSystem2_49741719/Engineering_and_Operations_in_the_Bell_System_2ed_1984
 | title = Engineering and Operations in the Bell System, 2nd Ed
 | last = Rey
 | first = R. F.
 | date = 1984
 | publisher = Bell Telephone Laboratories
 | access-date = 19 March 2017
 | page = 267}}</ref> such as tone or no tone and [[Ground (electricity)|ground]] [[electrical connection|connection]] versus battery connection. Note that if off-hook pertains to one state, [[on-hook]] pertains to the other.
* The active state (i.e., a closed loop ([[short circuit]] between the wires) of a [[subscriber line]] or [[Private branch exchange|PBX]] user loop)
* An operating state of a communications link in which [[transmission (telecommunications)|data transmission]] is enabled either for (a) voice or data communications or (b) [[telecommunications network|network]] signaling.<ref>[[Federal Standard 1037C]]</ref><ref>[[MIL-STD-188]]</ref>

On an ordinary two-wire telephone line, off-hook status is communicated to the [[telephone exchange]] by a resistance short across the pair. When an off-hook condition persists without dialing, for example because the handset has fallen off or the cable has been flooded, it is treated as a ''permanent loop'' or [[permanent signal]].

The act of ''going off-hook'' is also referred to as ''seizing'' the line or channel.