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Ground Start Trunk
{{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] |
Telephony
Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is intimately linked to the invention and development of the telephone. Telephony is commonly referred to as the construction or operation of telephones and telephonic systems and as a system of telecommunications in which telephonic equipment is employed in the transmission of speech or other sound between points, with or without the use of wires. The term is also used frequently to refer to computer hardware, software, and computer network systems, that perform functions traditionally performed by telephone equipment. In this context the technology is specifically referred to as Internet telephony, or voice over Internet Protocol (VoIP). Overview The first telephones were connected directly in pairs. Each user had a separate telephone wired ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ringing Signal
A ringtone, ring tone or ring is the sound made by a telephone to indicate an incoming call. Originally referring to and made by the electromechanical striking of bells, the term now refers to any sound on any device alerting of a new incoming call—up to and including recordings of original telephone bells. Electronic telephones, especially smartphones, are manufactured with a preloaded selection of ringtones. Customers can buy or generate custom ringtones for installation on the device. Background and history A telephone rings when the telephone network indicates an incoming call, so that the recipient is alerted of the call attempt. Landline telephones typically receive an electric alternating current signal, called ''power ringing'' or ''ringing signal'', generated by the telephone exchange to which the telephone is connected. The ringing current originally operated an electric bell. For mobile phones, the network sends a message to the recipient's device, which may activa ... [...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] |
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] |
DMS-100
The DMS-100 is a member of the Digital Multiplex System (DMS) product line of telephone exchange switches manufactured by Northern Telecom. Designed during the 1970s and released in 1979, it can control 100,000 telephone lines. The purpose of the DMS-100 Switch is to provide local service and connections to the PSTN public telephone network. It is designed to deliver services over subscribers' telephone lines and trunks. It provides plain old telephone service (POTS), mobility management for cellular phone systems, sophisticated business services such as automatic call distribution (ACD), Integrated Services Digital Network (ISDN), and Meridian Digital Centrex (MDC), formerly called Integrated Business Network (IBN). It also provides Intelligent Network functions (AIN, CS1-R, ETSI INAP). It is used in countries throughout the world. There are also DMS-200 and DMS-250 variants for tandem switches. Much of the hardware used in the DMS-100, with the possible exception of the line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossbar Switch
In electronics and telecommunications, a crossbar switch (cross-point switch, matrix switch) is a collection of switches arranged in a matrix configuration. A crossbar switch has multiple input and output lines that form a crossed pattern of interconnecting lines between which a connection may be established by closing a switch located at each intersection, the elements of the matrix. Originally, a crossbar switch consisted literally of crossing metal bars that provided the input and output paths. Later implementations achieved the same switching topology in solid-state electronics. The crossbar switch is one of the principal telephone exchange architectures, together with a rotary switch, memory switch, and a crossover switch. General properties A crossbar switch is an assembly of individual switches between a set of inputs and a set of outputs. The switches are arranged in a matrix. If the crossbar switch has M inputs and N outputs, then a crossbar has a matrix with ''M'' × ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trunking
In telecommunications, trunking is a technology for providing network access to multiple clients simultaneously by sharing a set of circuits, carriers, channels, or frequencies, instead of providing individual circuits or channels for each client. This is reminiscent to the structure of a tree with one trunk and many branches. Trunking in telecommunication originated in telegraphy, and later in telephone systems where a trunk line is a communications channel between telephone exchanges. Other applications include the trunked radio systems commonly used by police agencies. In the form of link aggregation and VLAN tagging, trunking has been applied in computer networking. Telecommunications A trunk line is a circuit connecting telephone switchboards (or other switching equipment), as distinguished from local loop circuit which extends from telephone exchange switching equipment to individual telephones or information origination/termination equipment. Trunk lines are used fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clearing (telecommunications)
Clearing, in telecommunications means: * A sequence of events used to disconnect a call and return to the ready state for the next call setup. It is sometimes, particularly in the context of common-channel signaling, called teardown. * Removal of data from an automated information system (AIS), its storage devices, and other peripheral devices with storage capacity, in such a way that the data may not be reconstructed using normal system capabilities (i.e. through the keyboard). ''Note:'' An AIS need not be disconnected from any external network before clearing takes place. Clearing enables a product to be reused within, but not outside of, a secure facility. It does not produce a declassified product by itself, but may be the first step in the declassification process. See also * Disengagement originator * National Information Systems Security Glossary Committee on National Security Systems Instruction No. 4009, National Information Assurance Glossary, published by the Un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disconnect 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] |
Off-hook
In telephony, on-hook and off-hook are two states of a communication circuit. On subscriber telephones the states are produced by placing the handset onto or off the hookswitch. Placing the circuit into the off-hook state is also called ''seizing the line''. ''Off-hook'' originally referred to the condition that prevailed when telephones had a separate earpiece (''receiver''), which hung from its switchhook until the user initiated a telephone call by removing it. When off hook the weight of the receiver no longer depresses the spring-loaded switchhook, thereby connecting the instrument to the telephone line. Off-hook The term off-hook has the following meanings: * The condition that exists when a telephone or other user instrument is in use, i.e., during dialing or communicating. * 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terminal (telecommunication)
In the context of telecommunications, a terminal is a device which ends a telecommunications link and is the point at which a signal enters or leaves a network. Examples of terminal equipment include telephones, fax machines, computer terminals, printers and workstations. An end instrument is a piece of equipment connected to the wires at the end of a telecommunications link. In telephony, this is usually a telephone connected to a local loop. End instruments that relate to data terminal equipment include printers, computers, barcode readers, automated teller machines (ATMs) and the console ports of routers. See also * Communication endpoint * Data terminal equipment * End system * Host (network) * Node (networking) * Terminal equipment In telecommunication, the term terminal equipment has the following meanings: * Communications equipment at either end of a communications link, used to permit the stations involved to accomplish the mission for which the link was estab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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