Signaling (telecommunications)wikipedia
In telecommunication, signaling is the use of signals for controlling communications.
signalsignalingsignallingout-of-band signalingsignalscontrol signalout-of-bandout-of-band signallingtelecommunication signalingsignaling protocol

In-band signaling

in-band signalingin-bandin-band signalling
In the public switched telephone network (PSTN), in-band signaling is the exchange of call control information within the same physical channel, or within the same frequency band, that the telephone call itself is using.
In telecommunications, in-band signaling is the sending of control information within the same band or channel used for voice or video.

Dual-tone multi-frequency signaling

DTMFtouch-tonetouch tone
An example is dual-tone multi-frequency signaling (DTMF), which is used on most telephone lines to customer premises.
Dual-tone multi-frequency signaling (DTMF) is an in-band telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers.

Signalling System No. 7

SS7SS7 networkCCS7
Out-of-band signaling has been used since Signaling System No. 6 (SS6) was introduced in the 1970s, and also in Signalling System No. 7 (SS7) in 1980 which became the standard for signaling among exchanges ever since.
Signaling System No. 7 (SS7) is a set of telephony signaling protocols developed in 1975, which is used to set up and tear down most of the world's public switched telephone network (PSTN) telephone calls.

Signaling System No. 6

Out-of-band signaling has been used since Signaling System No. 6 (SS6) was introduced in the 1970s, and also in Signalling System No. 7 (SS7) in 1980 which became the standard for signaling among exchanges ever since.
SS6 or CCITT No 6 Signalling System was introduced in the 1970s as an early common channel signalling method for telephone trunks between International Switching Centres (ISCs).

Line signaling

line signalingline signallingsupervision
Line signaling is concerned with conveying information on the state of the line or channel, such as on-hook, off-hook (answer supervision and disconnect supervision, together referred to as supervision), ringing current (alerting), and recall.
Line signaling is a class of telecommunications signaling protocols.

Communication channel

channelcommunication channelchannels
Out-of-band signaling is telecommunication signaling on a dedicated channel separate from that used for the telephone call.
The information is carried through the channel by a signal.

Signal

signalsignalselectrical signal
In telecommunication, signaling is the use of signals for controlling communications.
In telephone networks, signaling, for example common-channel signaling, refers to phone number and other digital control information rather than the actual voice signal.

Blue box

blue box2600 Hzblue boxes
In the middle 20th century, supervision signals on long-distance trunks in North America were usually inband, for example at 2600 Hz, necessitating a notch filter to prevent interference.
Instead, signaling occurs on an out-of-band channel that cannot be accessed from the line the caller is using, a system called Common Channel Interoffice Signaling or CCIS.

Public switched telephone network

public switched telephone networkPSTNtelephone network
In the public switched telephone network (PSTN), in-band signaling is the exchange of call control information within the same physical channel, or within the same frequency band, that the telephone call itself is using.
Bells were soon added to stations for signaling, so an attendant no longer needed to wait for the whistle.

Pulse dialing

pulse dialingdial pulsepulse dialling
In the first half of the 20th century, addressing formation is done by using a rotary dial, which rapidly breaks the line current into pulses, with the number of pulses conveying the address.
Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit.

Rotary dial

rotary dialdialrotary telephone
In the first half of the 20th century, addressing formation is done by using a rotary dial, which rapidly breaks the line current into pulses, with the number of pulses conveying the address.
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing.

Multi-frequency signaling

multi-frequencyMFmultifrequency
Most forms of R2 register signaling are compelled (see R2 signaling), while R1 multi-frequency signaling is not.
In telephony, multi-frequency signaling (MF) is a signaling system that was introduced by the Bell System after World War II.

Channel-associated signaling

channel-associated signalingCASchannel-associated-signalling
Channel-associated signaling (CAS) employs a signaling channel which is dedicated to a specific bearer channel.
Channel-associated signaling (CAS), also known as per-trunk signaling (PTS), is a form of digital communication signaling.

Common-channel signaling

common-channel signalingcommon channel signalingcommon channel signalling
Common-channel signaling (CCS) employs a signaling channel which conveys signaling information relating to multiple bearer channels.
In telephony, common-channel signaling (CCS), in the US also common-channel interoffice signaling (CCIS), is the transmission of signaling information (control information) on a separate channel than the data, and, more specifically, where that signaling channel controls multiple data channels.

E and M signaling

E&M
E and M signaling is a type of supervisory line signaling that uses DC signals on separate leads, called the "E" lead and "M" lead, traditionally used in the telecommunications industry between telephone switches.

2600 hertz

2600 hertz2600
2600 Hz is a frequency in hertz (cycles per second) that was used by AT&T as a steady signal to mark currently unused long-distance telephone lines.

Metering pulse

metering pulse
In telecommunications, metering pulses are telephone signals sent by telephone exchanges to metering boxes and payphones aimed at informing the latter of the cost of ongoing telephone calls.

Signaling protocol

signaling protocolsignalling protocolsignaling
Signaling is used to identify the state of connection between telephones or VOIP terminals (IP telephone or PCs or VoWLAN units).

Telecommunication circuit

circuittelecommunication circuitcircuits
This may constitute an information exchange concerning the establishment and control of a telecommunication circuit and the management of the network—in contrast to manual setup of circuits by users or administrators, for example the sending of a signal from the transmitting end of a telecommunication circuit to inform a user at the receiving end that a message is to be sent.

Telephone

telephonephonetelephones
In the early days of telephony, with operator handling calls, the addressing formation is by voice as "Operator, connect me to Mr. Smith please".
Signalling began in an appropriately primitive manner.

Supervision (telephony)

answer supervisiondisconnect supervisionindicate
Line signaling is concerned with conveying information on the state of the line or channel, such as on-hook, off-hook (answer supervision and disconnect supervision, together referred to as supervision), ringing current (alerting), and recall.
Some digital trunks, such as SS7, use out-of-band signaling to indicate termination of a call.

Session Initiation Protocol

SIPsession initiation protocolSession Initiation Protocol (SIP)
SIP is used for signaling and controlling multimedia communication sessions in applications of Internet telephony for voice and video calls, in private IP telephone systems, in instant messaging over Internet Protocol (IP) networks as well as mobile phone calling over LTE (VoLTE).

Session border controller

session border controllerSBCSession Border Controllers
A session border controller (SBC) is a device regularly deployed in Voice over Internet Protocol (VoIP) networks to exert control over the signaling and usually also the media streams involved in setting up, conducting, and tearing down telephone calls or other interactive media communications.

Single channel per carrier

single channel per carriersmall, independent channelsSCPC
Single channel per carrier (SCPC) refers to using a single signal at a given frequency and bandwidth.

Television transmitter

television transmittertransmitterTelevision and radio transmitter
A television transmitter is a device which broadcasts an electromagnetic signal to the television receivers.