Signaling (telecommunications)

signalsignalingsignallingout-of-band signalingsignalscontrol signalout-of-bandout-of-band signallingcall handling processescommunication systems
In telecommunication, signaling is the use of signals for controlling communications.wikipedia
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In-band signaling

in-bandin-band signallinginband
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.

Signal

signalselectrical signalelectrical signals
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.

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).

Public switched telephone network

PSTNtelephone networkpublic telephone 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.

Communication channel

channelchannelscommunications channel
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.

Line signaling

line signallingsupervisionLine
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, and hook flash.
Line signaling is a class of telecommunications signaling protocols.

Blue box

2600 Hzblue boxesblue boxing
In the middle 20th century, supervision signals on long-distance trunks in North America were primarily 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.

Rotary dial

dialrotary telephonerotary phone
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.

Pulse dialing

dial pulsepulse diallingpulse dial
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.

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 a telecommunication signaling system using the voice-frequency band over telephone lines between telephone equipment and other communications devices and switching centers.

Telecommunication circuit

circuitcircuitsconnection
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.
An electronic closed-loop path among two or more points used for signal transfer.

Channel-associated signaling

CASchannel associatedchannel-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 signalingcommoncommon channel
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.

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.

Supervision (telephony)

answer supervisioncalling party controldisconnect
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, and hook flash.
Some digital trunks, such as SS7, use out-of-band signaling to indicate termination of a call.

E and M signaling

E&M
E and M signaling (E&M) is an out-of-band channel-associated signaling system. The base system is intended for line signaling, but if decadic pulses are used it can also convey register information. E&M line signaling is however usually paired with DTMF register signaling.
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
By contrast, the L1 signaling system (which typically employs a 2280 Hz tone of various durations) is an in-band channel-associated signaling system as was the SF 2600 hertz system formerly used in the Bell System.
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.

Telephone

phonetelephonesLocal Telephone Service
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.

Metering pulse

Metering pulses (depending on the country, these are 50 Hz, 12 kHz or 16 kHz pulses sent by the exchange to payphones or metering boxes) are out-of-band (because they do not fall within the frequency range used by the telephony signal, which is 300 through 3400 Hz) and channel-associated. They are generally regarded as line signaling, although this is open to debate.
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

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

Telecommunication

telecommunicationscommunicationstelecom
In telecommunication, signaling is the use of signals for controlling communications.

Communication

communicationscommunicatecommunication skills
In telecommunication, signaling is the use of signals for controlling communications.

Telephone line

phone linelinetelephone lines
An example is dual-tone multi-frequency signaling (DTMF), which is used on most telephone lines to customer premises.

Ringing (telephony)

ringingmagenta boxcall bell
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, and hook flash.