In telecommunication, signalling (or signaling) has the following meanings: Copy of the original phone of Alexander Graham Bell at the Musée des Arts et Métiers in Paris Telecommunication is the transmission of signals over a distance for the purpose of communication. ...

• The use of signals for controlling communications.
• In a telecommunications network, the information exchange concerning the establishment and control of a connection and the management of the network, in contrast to user information transfer.
• The sending of a signal from the transmitting end of a circuit to inform a user at the receiving end that a message is to be sent.

Signalling systems can be classified according to their principal properties, some of which are described below: The term communications is used in a number of disciplines: Communications, also known as communication studies is the academic discipline which studies communication, generally seen as a mixture between media studies and linguistics. ... A telecommunications network is a network of telecommunications links arranged so that messages may be passed from one part of the network to another over multiple links. ... The ASCII codes for the word Wikipedia represented in binary, the numeral system most commonly used for encoding computer information. ... A telecommunication circuit is defined as follows: The complete path between two terminals over which one-way or two-way communications may be provided. ... In telecommunications, information transfer is the process of moving messages containing user information from a source to a sink. ... A telecommunication circuit is defined as follows: The complete path between two terminals over which one-way or two-way communications may be provided. ... Message in its most general meaning is an object of communication. ...

In-Band Signalling versus Out-Of-Band Signalling

In the public switched telephone network, (PSTN), in-band signalling is the exchange of signalling (call control) information within the same channel that the telephone call itself is using. An example is DTMF signalling. It has been suggested that Office classification be merged into this article or section. ... A DTMF telephone keypad Dual-tone multi-frequency (DTMF) signaling is used for telephone signaling over the line in the voice-frequency band to the call switching center. ...

Out-of-band signalling is telecommunication signalling (exchange of information in order to control a telephone call) that is done on a channel that is dedicated for the purpose and separate from the channels used for the telephone call. Out-of-band signalling is used in Signalling System #7 (SS7), the standard for the signalling that has controlled the world's phone calls for some twenty years. Signalling System #7 (SS7) is a set of telephony signalling protocols which are used to set up the vast majority of the worlds PSTN telephone calls. ...

Line Signalling versus Register Signalling

Line signalling is concerned with conveying information on the state of the line or channel, such as on-hook, off-hook (together referred to as supervision), ringing current (alerting), and recall. In the middle 20th Century, supervision signals on long trunks in North America were usually inband, for example at 2600 Hz, necessitating a notch filter to prevent interference. Late in the century, all supervisory signals were out of band. Line signaling is category of telecommunications signaling protocols. ... Supervision can refer to: SuperVision Videogame system A tutorial in Britain This is a disambiguation page — a list of pages that otherwise might share the same title. ... 2600 Hz is the frequency in hertz (cycles per second) that AT&T formerly put as a steady signal on any long-distance telephone line that was not currently in use. ... A notch filter, also called a band-stop filter, sometimes a narrow band-pass filter, or T-notch filter, is an electronic filter typically used when the high frequency and the low frequency are less than 1 to 2 decades apart (that is, the high frequency is less than 10...

Register signalling is concerned with conveying addressing information, such as the calling and/or called telephone number. In telecommunications, register signaling is concerned with conveying addressing information, such as the calling and/or called telephone number. ...

Channel-Associated Signalling versus Common-Channel Signalling

Channel-Associated signalling employs a signalling channel which is dedicated to a specific bearer channel. Channel Associated Signaling CAS signaling is a form of digital communication signaling. ... B channel (bearer) is a telecommunications term which refers to the ISDN channel in which the primary data or voice communication is carried. ...

Common-Channel signalling is so-called, because it employs a signalling channel which conveys signalling information relating to multiple bearer channels. These bearer channels therefore have their signalling channel in common. Common Channel Signaling (CCS) is the transmission of signaling information out of the information band. ...

Compelled Signalling

The term Compelled signalling refers to the case where receipt of each signal needs to be explicitly acknowledged before the next signal is able to be sent. The term compelled signalling refers to a class of telecommunications signalling protocols where receipt of each discrete signal needs to be explicitly acknowledged before the next signal is able to be sent. ...

Most forms of R2 register signalling are compelled (see R2 signalling), while R1 multi-frequency is not. R2 is a 1960s- and 1970s-era Channel Associated Signalling signalling protocol used outside of North America to convey at least the following information along a telephone trunk: seizure of an idle DS0 channel, the called partys digits 1 through 10, the calling partys digits 1 through 10... In telephony Multi-Frequency (MF) is an outdated, in-band signaling technique. ...

The term is only relevant in the case of signalling systems that use discrete signals (e.g. a combination of tones to denote one digit), as opposed to signalling systems which are message-oriented (such as SS7 and ISDN Q.931) where each message is able to convey multiple items of information (e.g. multiple digits of the called telephone number).

Subscriber vs trunk signaling

Subscriber signaling is between the telephone and the telephone exchange. Trunk signaling is between exchanges. A telephone operator manually connecting calls with patch cables at a telephone switchboard. ...

Classification examples

Note that every signalling system can be characterized along each of the above axes of classification. A few examples:

• DTMF is an in-band, channel-associated register signalling system. It is not compelled.
• SS7 (e.g. TUP or ISUP) is an out-of-band, common-channel signalling system that incorporates both line and register signalling.
• Metering pulses (depending on the country, these are 50Hz, 12kHz or 16kHz 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 3400Hz) and channel-associated. They are generally regarded as line signaling, although this is open to debate.
• E&M signalling is an out-of-band channel-associated signalling system. The base system is intended for line signalling, but if decadic pulses are used it can also convey register information. E&M line signalling is however usually paired with DTMF register signalling.
• By contrast, the L1 signalling system (which typically employs a 2280Hz tone of various durations) is an in-band channel-associated signalling system as was the SF 2600 Hz system formerly used in the Bell System.
• Loop start, Ground start, Reverse Battery and Revertive Pulse systems are all DC, thus out of band, and all are channel-associated, since the DC currents are on the talking wires.

Whereas common-channel signaling systems are out-of-band by definition, and in-band signaling systems are also necessarily channel-associated, the above metering pulse example demonstrates that there exist channel-associated signaling systems which are out-of-band. Dual-tone multi-frequency (DTMF), also known as Touch Tone® is used for telephone signaling over the line in the voice frequency band to the call switching center. ... Signalling System #7 is a set of protocols defined by ITU-T, specifically in the Q.7* set of documents, used to set up telephone calls. ... In telecommunications signalling, metering pulses are signals sent by telephone exchanges to metering boxes and payphones aimed at informing the latter of the cost of ongoing telephone calls. ... Payphone A payphone or pay phone is a public telephone, with payment by inserting money (usually coins) or a debit card (a special telephone card or a multi-purpose card) or credit card before a call is made. ... E&M is a type of supervisory signaling traditionally used in the North American telecommunications industry. ... 2600 may refer to: 2600 Hz, the tone used by a blue box to gain control of telephone networks 2600: The Hacker Quarterly, a magazine named after the 2600 Hz tone used in phreaking Atari 2600 video game console 2600 (year) ARP 2600 analog synthesizer Category: ... The Bell System was a trademark and service mark used by the US telecommunications company American Telephone & Telegraph Company (AT&T) and its affiliated companies to co-brand their extensive circuit-switched telephone network and their affiliations with each other. ... In telecommunications, a loop start is a supervisory signal given by a telephone or PBX in response to the completion of the loop path. ... In telephony, a ground start is a method of signaling from a terminal or subscriber local loop to a telephone exchange, in which method a cable pair is temporarily grounded to request dial tone. ...

asif signal

Sources

• Federal Standard 1037C
• MIL-STD-188