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Loop Start
Loop start is a telecommunications supervisory protocol between a central office or private branch exchange (PBX) and a subscriber telephone or other terminal for the purpose of starting and terminating a telephone call. It is the simplest of the telephone signaling systems, and uses the presence or absence of loop current to indicate the off-hook and on-hook loop states, respectively. It is used primarily for subscriber line signaling. An extension of the protocol that adds disconnect supervision is often called kewlstart. Protocol operation When the telephone is ''on-hook'', the potential of the ring conductor of the local loop is held at a nominal level of -48V DC with respect to the tip conductor, provided by the telephone exchange or a foreign exchange station (FXS) interface. When the terminal initiates use of the line, it causes current to flow by closing the loop, and this signals the exchange to provide dial tone on the line and to expect dial signals, in form of DTMF digi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecommunications
Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that feasible with the human voice, but with a similar scale of expediency; thus, slow systems (such as postal mail) are excluded from the field. The transmission media in telecommunication have evolved through numerous stages of technology, from beacons and other visual signals (such as smoke signals, semaphore telegraphs, signal flags, and optical heliographs), to electrical cable and electromagnetic radiation, including light. Such transmission paths are often divided into communication channels, which afford the advantages of multiplexing multiple concurrent communication sessions. ''Telecommunication'' is often used in its plural form. Other examples of pre-modern long-distance communication included audio messages, such as coded drumb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Call Collision
In telecommunications, a call collision (commonly known as glare) is one of two things: #The contention that occurs when a terminal and data circuit-terminating equipment ( DCE) specify the same communication channel at the same time to transfer a call request and handle an incoming call. When call collision occurs, the DCE proceeds with the call request and cancels the incoming call. #The condition that occurs when a trunk or channel is seized at both ends simultaneously. Glare can sometimes be experienced as trying to make a call out on a PBX, and instead being connected to an incoming call. This can happen at home too, if a call out is made at the exact second that a call is about to start ringing in. Multi-line hunting attempts to avoid glare by selecting circuits in opposite preference order so the highest numbered line, which is last choice for incoming calls, is first choice for outgoing calls, like so: incoming -->1 2 3 4 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foreign Exchange Station
Foreign exchange service (FX) is an access service in a telecommunications network in which a telephone in a given exchange area is connected, via a private line, as opposed to a switched line, to a telephone exchange or central office in another exchange area, called the ''foreign'' exchange, rather than the local exchange area where the subscriber station equipment is located. To call originators, it appears that the called party having the FX service is located in the foreign exchange area. It is assigned a telephone number of the foreign exchange. The telecommunication circuit between central offices that implements foreign exchange service has complementary interface types at each end. At the foreign central office that provides the service, the interface is called the foreign exchange office (FXO) end, and at the end where the subscriber station is connected, it provides the foreign exchange station (FXS) interface. Purpose Basic telephony terminology distinguishes two types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterisk (PBX)
Asterisk is a software implementation of a private branch exchange (PBX). In conjunction with suitable telephony hardware interfaces and network applications, Asterisk is used to establish and control telephone calls between telecommunication endpoints, such as customary telephone sets, destinations on the public switched telephone network (PSTN), and devices or services on voice over Internet Protocol (VoIP) networks. Its name comes from the asterisk (*) symbol for a signal used in dual-tone multi-frequency (DTMF) dialing. Asterisk was created in 1999 by Mark Spencer of Digium, which since 2018 is a division of Sangoma Technologies Corporation. Originally designed for Linux, Asterisk runs on a variety of operating systems, including NetBSD, OpenBSD, FreeBSD, macOS, and Solaris, and can be installed in embedded systems based on OpenWrt. Features The Asterisk software includes many features available in commercial and proprietary PBX systems: voice mail, conference callin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forward Disconnect
In telecommunication, supervision is the monitoring of a telecommunication circuit for telephony to convey to an operator, user, or a switching system, information about the operational state of the circuit. The typical operational states of trunks and lines are the idle and busy states, seizure, and disconnect. The states are indicated by various electrical signals and electrical conditions depending on the type of circuit, the type of terminating equipment, and the type of intended service. Answer and disconnect supervision are functions of line signaling that convey circuit seizure and disconnect. Answer supervision indicates that a call has been answered. Disconnect supervision provides a signal that the call has been disconnected. For example, the called party may indicate to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line, or the called party indicates to the exchange that the call is being answered. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calling Party Control
In telecommunication, supervision is the monitoring of a telecommunication circuit for telephony to convey to an operator, user, or a switching system, information about the operational state of the circuit. The typical operational states of trunks and lines are the idle and busy states, seizure, and disconnect. The states are indicated by various electrical signals and electrical conditions depending on the type of circuit, the type of terminating equipment, and the type of intended service. Answer and disconnect supervision are functions of line signaling that convey circuit seizure and disconnect. Answer supervision indicates that a call has been answered. Disconnect supervision provides a signal that the call has been disconnected. For example, the called party may indicate to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line, or the called party indicates to the exchange that the call is being answered. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hook Flash
On analog telephone lines with special services, a flash or register-recall signal is used to control functions on the public telephone exchange, PBX or VoIP ATA. The term "register-recall" in Europe refers to sending a discrete signal to alert the "register" — the logical system controlling a telephone exchange, that it should accept commands from the end user in the middle of a call. The register was normally disconnected from the circuit once a call was setup. In contemporary telephone systems, the functions of the register are carried out by software and computer hardware, but in previous generations of electromechanical exchanges, using technology such crossbar or Reed relay, the register was often a system of analog electronics or even relay logic. The term "Flash" or "Hook Flash" is commonly used in North America, while in Europe a similar signal is referred to as a register-recall or more commonly "Recall" or simply the "R" button. These signals perform similar functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Switching Interval
In telecommunication, supervision is the monitoring of a telecommunication circuit for telephony to convey to an operator, user, or a switching system, information about the operational state of the circuit. The typical operational states of trunks and lines are the idle and busy states, seizure, and disconnect. The states are indicated by various electrical signals and electrical conditions depending on the type of circuit, the type of terminating equipment, and the type of intended service. Answer and disconnect supervision are functions of line signaling that convey circuit seizure and disconnect. Answer supervision indicates that a call has been answered. Disconnect supervision provides a signal that the call has been disconnected. For example, the called party may indicate to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line, or the called party indicates to the exchange that the call is being answered. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open Loop Disconnect
In telecommunication, supervision is the monitoring of a telecommunication circuit for telephony to convey to an operator, user, or a switching system, information about the operational state of the circuit. The typical operational states of trunks and lines are the idle and busy states, seizure, and disconnect. The states are indicated by various electrical signals and electrical conditions depending on the type of circuit, the type of terminating equipment, and the type of intended service. Answer and disconnect supervision are functions of line signaling that convey circuit seizure and disconnect. Answer supervision indicates that a call has been answered. Disconnect supervision provides a signal that the call has been disconnected. For example, the called party may indicate to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line, or the called party indicates to the exchange that the call is being answered. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foreign Exchange Office
Foreign exchange service (FX) is an access service in a telecommunications network in which a telephone in a given exchange area is connected, via a private line, as opposed to a switched line, to a telephone exchange or central office in another exchange area, called the ''foreign'' exchange, rather than the local exchange area where the subscriber station equipment is located. To call originators, it appears that the called party having the FX service is located in the foreign exchange area. It is assigned a telephone number of the foreign exchange. The telecommunication circuit between central offices that implements foreign exchange service has complementary interface types at each end. At the foreign central office that provides the service, the interface is called the foreign exchange office (FXO) end, and at the end where the subscriber station is connected, it provides the foreign exchange station (FXS) interface. Purpose Basic telephony terminology distinguishes two types ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Answer Supervision
In telecommunication, supervision is the monitoring of a telecommunication circuit for telephony to convey to an operator, user, or a switching system, information about the operational state of the circuit. The typical operational states of trunks and lines are the idle and busy states, seizure, and disconnect. The states are indicated by various electrical signals and electrical conditions depending on the type of circuit, the type of terminating equipment, and the type of intended service. Answer and disconnect supervision are functions of line signaling that convey circuit seizure and disconnect. Answer supervision indicates that a call has been answered. Disconnect supervision provides a signal that the call has been disconnected. For example, the called party may indicate to the telephone exchange that the call is being disconnected by the called party by allowing loop current to flow in the line, or the called party indicates to the exchange that the call is being answered. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Start
{{refimprove, date=January 2008 In telephony, ground start is a method of signaling from a terminal of a subscriber local loop to a telephone exchange, where one side of a cable pair is temporarily grounded to request dial tone. Most middle 20th-century American payphones used coin-first ground start lines, with the starting ground connection provided by the coin itself, bridging a set of contacts as it passes through the coin chute. Ground start trunk Telephone companies typically provide two types of dial tone switched circuits – ground start and loop start. Private branch exchanges (PBX) work best on ground start trunks because those trunks can give them an on hook signal allowing for timely clearing. Normal single line telephones and key systems typically work on loop start lines. On loop start lines the PBX and central office may inadvertently seize the line simultaneously, a condition called ''glare'', resulting in call collision since neither gets the expected response ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
