On- and Off-hook

off-hookon-hookon hookhang uphanging upoff hookpick-up
In telephony, on-hook and off-hook refer to the two possible states of a receiver.wikipedia
60 Related Articles

Permanent signal

left off-hookpermanent loop
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.
Permanent Signal (PS) in US telephony jargon, or Permanent Loop in British usage, is a condition in which a POTS line is off-hook without connection for an extended period of time.

Telephone exchange

exchangescentral officeexchange
On an ordinary two-wire telephone line, off-hook status is communicated to the telephone exchange by a resistance short across the pair.
An off-hook condition represents a circuit that is in use, e.g., when a phone call is in progress.

Telephone

phonetelephonesLocal Telephone Service
1) The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating. 1) The condition that exists when a telephone or other user 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 thereby disconnecting the idle instrument (except its bell) from the telephone line.
The landline telephone contains a switchhook (A4) and an alerting device, usually a ringer (A7), that remains connected to the phone line whenever the phone is "on hook" (i.e. the switch (A4) is open), and other components which are connected when the phone is "off hook".

Single-frequency signaling

SF tonesingle frequencysingle frequency tones
2) One of two possible signaling states, such as tone or no tone, or ground connection versus battery connection. Note: if on-hook pertains to one state, off-hook pertains to the other.
The SF tone is present in the on-hook or idle state and absent during the seized state.

Hook flash

flashesRecallswitchhook flash
Hook flash
Hook flash or flash (known in the UK as "recall") is a button on a telephone that simulates quickly hanging up then picking up again (a quick off-hook/on-hook/off-hook cycle).

Telephone hook

switchhookhandset cradlehook switch
Off-hook originally referred to the condition that prevailed when telephones had a separate earpiece (i.e., receiver), which hung from its switchhook until the user wished to activate it. The weight of the receiver no longer depresses the spring-loaded switchhook, thereby connecting the instrument to the telephone line. 1) The condition that exists when a telephone or other user 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 thereby disconnecting the idle instrument (except its bell) from the telephone line.
When the handset is on the cradle, the telephone is said to be "on-hook", or ready for a call.

Off-hook tone

high toneHowler/off-hook warningoff-hook
Off-hook tone
The off-hook tone (also receiver off-hook tone, off-hook warning, or howler tone) is a telephony signal used to alert a user that the telephone has been left off-hook without use for an extended period, effectively disabling the telephone line.

Line signaling

line signallingsupervisionLine
Line signaling
Line signaling is responsible for off-hook, ringing signal, answer, ground start, on-hook unidirectional supervision messaging in each direction from calling party to called party and vice versa.

Supervision (telephony)

answer supervisioncalling party controldisconnect
Disconnect supervision
A channel is idle/on hook when there is no call on it or seized/off-hook/energized by an active call.

Telephony

digital telephonytelephonedigital
In telephony, on-hook and off-hook refer to the two possible states of a receiver.

Telephone line

phone linelinetelephone lines
Off-hook originally referred to the condition that prevailed when telephones had a separate earpiece (i.e., receiver), which hung from its switchhook until the user wished to activate it. The weight of the receiver no longer depresses the spring-loaded switchhook, thereby connecting the instrument to the telephone line. 1) The condition that exists when a telephone or other user 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 thereby disconnecting the idle instrument (except its bell) from the telephone line.

User (telecommunications)

userUsersinternet users
1) The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating. 1) The condition that exists when a telephone or other user 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 thereby disconnecting the idle instrument (except its bell) from the telephone line.

Dialling (telephony)

dialingDiallingdialpad
1) The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating.

Signaling (telecommunications)

signalsignalingsignalling
2) One of two possible signaling states, such as tone or no tone, or ground connection versus battery connection. Note: if on-hook pertains to one state, off-hook pertains to the other. 2) A general description of one of two possible signaling states at an interface between telecommunications systems, such as tone or no tone and ground connection versus battery connection. Note that if off-hook pertains to one state, on-hook pertains to the other. 4) An operating state of a communications link in which data transmission is enabled either for (a) voice or data communications or (b) network signaling.

Ground (electricity)

groundgroundinggrounded
2) One of two possible signaling states, such as tone or no tone, or ground connection versus battery connection. Note: if on-hook pertains to one state, off-hook pertains to the other. 2) A general description of one of two possible signaling states at an interface between telecommunications systems, such as tone or no tone and ground connection versus battery connection. Note that if off-hook pertains to one state, on-hook pertains to the other.

Electrical connector

connectorconnectorselectrical connection
2) One of two possible signaling states, such as tone or no tone, or ground connection versus battery connection. Note: if on-hook pertains to one state, off-hook pertains to the other. 2) A general description of one of two possible signaling states at an interface between telecommunications systems, such as tone or no tone and ground connection versus battery connection. Note that if off-hook pertains to one state, on-hook pertains to the other.

Short circuit

short-circuitshortelectrical short
3) The active state (i.e., a closed loop (short circuit between the wires) of a subscriber line or PBX user loop)

Local loop

subscriber lineloopsubscriber loop
3) The active state (i.e., a closed loop (short circuit between the wires) of a subscriber line or PBX user loop)

Business telephone system

PBXprivate branch exchangekey telephone system
3) The active state (i.e., a closed loop (short circuit between the wires) of a subscriber line or PBX user loop)

Data

statistical datascientific datadatum
4) An operating state of a communications link in which data transmission is enabled either for (a) voice or data communications or (b) network signaling.

Transmission (telecommunications)

transmissiontransmittransmissions
4) An operating state of a communications link in which data transmission is enabled either for (a) voice or data communications or (b) network signaling. 4) An operating state of a telecommunication circuit in which transmission is disabled and a high impedance, or "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.

Telecommunications network

networkcommunication networkcommunications network
4) An operating state of a communications link in which data transmission is enabled either for (a) voice or data communications or (b) network signaling.

Clearing (telecommunications)

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

In-ear monitor

earpiecein-ear monitorsin ear monitors
1) The condition that exists when a telephone or other user 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 thereby disconnecting the idle instrument (except its bell) from the telephone line.

Telecommunication circuit

circuitcircuitsconnection
4) An operating state of a telecommunication circuit in which transmission is disabled and a high impedance, or "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.