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Encyclopedia > PSTN

The public switched telephone network (PSTN) is the concatenation of the world's public circuit-switched telephone networks, in much the same way that the Internet is the concatenation of the world's public IP-based packet-switched networks. Originally a network of fixed-line analog telephone systems, the PSTN is now almost entirely digital, and now includes mobile as well as fixed telephones. In telecommunication, the term circuit switching has the following meanings: 1. ... This article needs to be cleaned up to conform to a higher standard of quality. ... The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across a packet-switched internetwork. ... In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ... Motorola Black Razr mobile phone A mobile phone, also known as a cell phone, is a portable electronic device which behaves as a normal telephone whilst being able to move over a wide area (compare cordless phone which acts as a telephone only within a limited range). ...


The PSTN is largely governed by technical standards created by the ITU-T, and uses E.163/E.164 addresses (known more commonly as telephone numbers) for addressing. The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Union (ITU) and is based in Geneva, Switzerland. ... E.163 was an ITU-T standard for describing telephone numbers for the public voice network (PSTN). ... This article needs to be cleaned up to conform to a higher standard of quality. ...


Architecture and context

The PSTN was the earliest example of traffic engineering to deliver Quality of Service guarantees. A.K. Erlang is documented in history as proving the mathematical foundations of this. For another meaning of the term traffic engineering, please see transport traffic engineering. ... In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service (QoS) refers to the probability of the telecommunication network meeting a given traffic contract, or in many cases is used informally to refer the probability of a packet succeeding in passing between two... Agner Krarup Erlang (January 1, 1878–February 3, 1929) was a Danish mathematician, statistician, and engineer who invented the fields of queueing theory and traffic engineering. ...


In the 1970s the telecommunications industry conceived that digital services would follow much the same pattern as voice services, and conceived a vision of end-to-end circuit switched services, known as the Broadband Integrated Services Digital Network (B-ISDN). The B-ISDN vision has been overtaken by the disruptive technology of the Internet. This article provides extensive lists of events and significant personalities of the 1970s. ... In telecommunication, the term circuit switching has the following meanings: 1. ... In the 1970s the telecommunications industry conceived that digital services would follow much the same pattern as voice services, and conceived a grandiose vision of end_to_end circuit switched services, known as the Broadband Integrated Services Digital Network (B-ISDN). ... A disruptive technology is a new technological innovation, product, or service that eventually overturns the existing dominant technology in the market, despite the fact that the disruptive technology is both radically different than the leading technology and that it often initially performs worse than the leading technology according to existing...


Only the very oldest and most backward parts of the telephone network still use analog technology for anything other than the last mile loop to the end user, and in recent years digital services have been increasingly rolled out to end users using services such as DSL, ISDN and Cable Systems. The last mile is the final leg of delivering communications connectivity to a resident or customer. ... DSL Modem Digital Subscriber Line, or DSL, is a family of technologies that provide a digital connection over the copper wires of the local telephone network. ... ISDN is also short for isosorbide dinitrate Integrated Services Digital Network (ISDN) is a type of circuit switched telephone network system, designed to allow digital (as opposed to analog) transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds, than available with analog...


Many observers believe that the long term future of the PSTN is to be just one application of the Internet - however, the Internet has some way to go before this transition can be made. The Quality of Service guarantee is one aspect that needs to be improved on in the Voice over IP technology. In the fields of packet-switched networks and computer networking, the traffic engineering term Quality of Service (QoS) refers to the probability of the telecommunication network meeting a given traffic contract, or in many cases is used informally to refer the probability of a packet succeeding in passing between two... Voice over IP (also called VoIP, IP Telephony, Internet telephony, and has also been branded Digital Phone) is the routing of voice conversations over the Internet or any other IP network. ...


There are a number of large private telephone networks which are not linked to the PSTN, usually for military purposes. There are also private networks run by large companies which are linked to the PSTN only through limited gateways, like a large PABX system. PBX redirects here. ...


Technology overview

The basic digital circuit in the PSTN is a 64-kilobits-per-second channel, originally designed by Bell Labs, called a "DS0" or Digital Signal 0. To carry a typical phone call from a calling party to a called party, the audio sound is digitized at an 8 kHz sample rate using 8-bit pulse code modulation. The call is then transmited from one end to another via telephone exchanges. The call is switched using a signalling protocol (SS7) between the telephone exchanges under an overall routing strategy. In telecommunications and computing, bit rate (sometimes written bitrate) is the frequency at which bits are passing a given (physical or metaphorical) point. It is quantified using the bit per second (bit/s) unit. ... Bell Telephone Laboratories or Bell Labs was originally the research and development arm of the United States Bell System, and was the premier corporate facility of its type, developing a range of revolutionary technologies from telephone switches to specialized coverings for telephone cables, to the transistor. ... In T-carrier systems Digital signal 0 (DS0) is a basic digital signaling rate of 64 kb/s, corresponding to the capacity of one voice-frequency-equivalent channel. ... The person who (or device that) initiates a telephone call over the public switched telephone network is the calling party. ... The person who (or device that) answers a telephone is the called party. ... Pulse-code modulation (PCM) is a modulation technique. ... In the field of telecommunications, a telephone exchange (US: telephone switch) is a piece of equipment that connects phone calls. ... In telecommunication, the term circuit switching has the following meanings: 1. ... In telecommunication, signaling has the following meanings: The use of signals for controlling communications. ... In computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. ... 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. ... Routing in the PSTN is the process by which telephone calls are routed around the public switched telephone network. ...


The DS0's are the basic granularity at which switching takes place in a telephone exchange. DS0's are also known as timeslots because they are multiplexed together in a time-division fashion. Multiple DS0's are multiplexed together on higher capacity circuits, such that 24 DS0's make a DS1 signal, which when carried on copper is the well-known, T-carrier system, T1 (the European equivalent is an E1, containing 32 64 kbit/s channels). In modern networks, this multiplexing is moved as close to the end user as possible, usually into cabinets at the roadside in residential areas, or into large business premises. In telecommunication, the term circuit switching has the following meanings: 1. ... In the field of telecommunications, a telephone exchange (US: telephone switch) is a piece of equipment that connects phone calls. ... Time Division Multiple Access (TDMA) is a technology for shared medium (usually radio) networks. ... In telecommunications, T-carrier is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America and Japan. ... In digital telecommunications, where a single physical wire can be used to carry many simultaneous voice conversations, worldwide standards have been created and deployed. ...


The timeslots are conveyed from the initial multiplexer to the exchange over a set of equipment collectively known as the access network. The access network and inter-exchange transport of the PSTN use synchronous optical transmission (SONET and SDH) technology, although some parts still use the older PDH technology. Synchronization is coordination with respect to time. ... Synchronous Optical Networking, commonly known as SONET, is a standard for communicating digital information over optical fiber. ... Synchronous Optical Networking, commonly known as SONET, is a standard for communicating digital information over optical fiber. ... The Plesiochronous Digital Hierarchy (PDH) is a technology used in telecommunications networks to transport large quantities of data over digital transport equipment such as fibre optic and microwave radio systems. ...


Within the access network, there are a number of reference points defined. Most of these are of interest mainly to ISDN but one - the V reference point - is of more general interest. This is the reference point between a primary multiplexer and an exchange. The protocols at this reference point were standardised in ETSI areas as the V5 interface. ISDN is also short for isosorbide dinitrate Integrated Services Digital Network (ISDN) is a type of circuit switched telephone network system, designed to allow digital (as opposed to analog) transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds, than available with analog... The European Telecommunications Standards Institute (ETSI) is a standardization organization of the telecommunications industry (equipment makers and network operators) in Europe, with worldwide projection. ... V5 is a set of protocols defined by ETSI by which a multiplexer in the access network of the PSTN can communicate with a telephone exchange. ...


See also


  Results from FactBites:
 
Public Switched Telephone Network - Wikipedia, the free encyclopedia (637 words)
The public switched telephone network (PSTN) is the concentration of the world's public circuit-switched telephone networks, in much the same way that the Internet is the concentration of the world's public IP-based packet-switched networks.
The PSTN is largely governed by technical standards created by the ITU-T, and uses E.163/E.164 addresses (known more commonly as telephone numbers) for ooo addressing.
The basic digital circuit in the PSTN is a 64-kilobits-per-second channel, originally designed by Bell Labs, called a "DS0" or Digital Signal 0.
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