32-411: GSTN may refer to: General Switched Telephone Network Goods and Services Tax Network , an Indian not-for-profit, non-government firm Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title GSTN . If an internal link led you here, you may wish to change the link to point directly to
64-471: A telephone call was accomplished by whistling loudly into the transmitter until the other party heard the alert. Bells were soon added to stations for signaling . Later telephone systems took advantage of the exchange principle already employed in telegraph networks. Each telephone was wired to a telephone exchange established for a town or area. For communication outside this exchange area, trunks were installed between exchanges. Networks were designed in
96-638: A benchmark for the development of the Telecommunications Industry Association 's TIA-TSB-116 standard on voice-quality recommendations for IP telephony, to determine acceptable levels of audio latency and echo. In most countries, the government has a regulatory agency dedicated to provisioning of PSTN services. The agency regulate technical standards, legal requirements, and set service tasks may be for example to ensure that end customers are not over-charged for services where monopolies may exist. These regulatory agencies may also regulate
128-414: A global telephone numbering plan allows telephones around the world to connect with each other. Commercialization of the telephone began shortly after its invention, with instruments operated in pairs for private use between two locations. Users who wanted to communicate with persons at multiple locations had as many telephones as necessary for the purpose. Alerting another user of the desire to establish
160-518: A hierarchical manner until they spanned cities, states, and international distances. Automation introduced pulse dialing between the telephone and the exchange so that each subscriber could directly dial another subscriber connected to the same exchange, but long-distance calling across multiple exchanges required manual switching by operators. Later, more sophisticated address signaling, including multi-frequency signaling methods, enabled direct-dialed long-distance calls by subscribers, culminating in
192-505: A network of fixed-line analog telephone systems, the PSTN is now predominantly digital in its core network and includes terrestrial cellular , satellite , and landline systems. These interconnected networks enable global communication, allowing calls to be made to and from nearly any telephone worldwide. Many of these networks are progressively transitioning to Internet Protocol to carry their telephony traffic. The technical operation of
224-425: A telephone exchange. A DS0 is also known as a timeslot because DS0s are aggregated in time-division multiplexing (TDM) equipment to form higher capacity communication links. A Digital Signal 1 (DS1) circuit carries 24 DS0s on a North American or Japanese T-carrier (T1) line, or 32 DS0s (30 for calls plus two for framing and signaling) on an E-carrier (E1) line used in most other countries. In modern networks,
256-490: Is by DTMF . Channel-associated signaling (CAS) employs a signaling channel that is dedicated to a specific bearer channel . Common-channel signaling (CCS) employs a signaling channel which conveys signaling information relating to multiple bearer channels. These bearer channels, therefore, have their signaling channel in common. Compelled signaling refers to signaling where the receipt of each signal from an originating register needs to be explicitly acknowledged before
288-432: Is then transmitted from one end to another via telephone exchanges. The call is switched using a call set up protocol (usually ISUP ) between the telephone exchanges under an overall routing strategy . The call is carried over the PSTN using a 64 kbit/s channel, originally designed by Bell Labs . The name given to this channel is Digital Signal 0 (DS0). The DS0 circuit is the basic granularity of circuit switching in
320-481: Is using. An example is dual-tone multi-frequency signaling (DTMF), which is used on most telephone lines to customer premises. Out-of-band signaling is telecommunication signaling on a dedicated channel separate from that used for the message. 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
352-465: The E1-carrier dedicated to signaling. 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 . Register signaling is concerned with conveying addressing information, such as the calling and/or called telephone number . In
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#1733084949937384-468: The Signalling System 7 (SS7) network that controlled calls between most exchanges by the end of the 20th century. The growth of the PSTN was enabled by teletraffic engineering techniques to deliver quality of service (QoS) in the network. The work of A. K. Erlang established the mathematical foundations of methods required to determine the capacity requirements and configuration of equipment and
416-496: The last mile to the end-user. However, digital technologies such as DSL , ISDN , FTTx , and cable modems were progressively deployed in this portion of the network, primarily to provide high-speed Internet access. As of 2023 , operators worldwide are in the process of retiring support for both last-mile analog telephony and ISDN, and transitioning voice service to Voice over IP via Internet access delivered either via DSL , cable modems or fiber-to-the-premises , eliminating
448-591: The network operators . The first company to be incorporated to provide PSTN services was the Bell Telephone Company in the United States. In some countries, however, the job of providing telephone networks fell to government as the investment required was very large and the provision of telephone service was increasingly becoming an essential public utility . For example, the General Post Office in
480-506: The PSTN adheres to the standards internationally promulgated by the ITU-T . These standards have their origins in the development of local telephone networks, primarily in the Bell System in the United States and in the networks of European ITU members. The E.164 standard provides a single global address space in the form of telephone numbers . The combination of the interconnected networks and
512-661: The United Kingdom brought together a number of private companies to form a single nationalized company . In more recent decades, these state monopolies were broken up or sold off through privatization . The architecture of the PSTN evolved over time to support an increasing number of subscribers, call volume, destinations, features, and technologies. The principles developed in North America and in Europe were adopted by other nations, with adaptations for local markets. A key concept
544-549: The aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony . The PSTN consists of telephone lines , fiber-optic cables , microwave transmission links, cellular networks , communications satellites , and undersea telephone cables interconnected by switching centers , such as central offices , network tandems , and international gateways, which allow telephone users to communicate with each other. Originally
576-435: The called telephone number). Subscriber signaling refers to the signaling between the telephone and the telephone exchange . Trunk signaling is the signaling between exchanges. Every signaling system can be characterized along each of the above axes of classification. A few examples: Whereas common-channel signaling systems are out-of-band by definition, and in-band signaling systems are also necessarily channel-associated,
608-413: The early days of telephony , with operator handling calls, the addressing formation is by voice as "Operator, connect me to Mr. Smith please". 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. Finally, starting in the second half of the century, address signaling
640-403: The establishment and control of a telecommunication circuit and the management of the network. Signaling systems may be classified based on several principal characteristics. 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 message (the callers' voice)
672-465: The exchanges are also digital, called circuits or channels. However analog two-wire circuits are still used to connect the last mile from the exchange to the telephone in the home (also called the local loop ). To carry a typical phone call from a calling party to a called party , the analog audio signal is digitized at an 8 kHz sample rate with 8-bit resolution using a special type of nonlinear pulse-code modulation known as G.711 . The call
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#1733084949937704-452: The expense and complexity of running two separate technology infrastructures for PSTN and Internet access. Several large private telephone networks are not linked to the PSTN, usually for military purposes. There are also private networks run by large companies that are linked to the PSTN only through limited gateways , such as a large private branch exchange (PBX). The task of building the networks and selling services to customers fell to
736-401: The intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=GSTN&oldid=977384383 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages General Switched Telephone Network The public switched telephone network ( PSTN ) is
768-547: The interface to end-users remaining the same. Several other European countries, including Estonia, Germany, Iceland, the Netherlands, Spain and Portugal, have also retired, or are planning to retire, their PSTN networks. Countries in other continents are also performing similar transitions. Signaling (telecommunications) In telecommunications , signaling is the use of signals for controlling communications . This may constitute an information exchange concerning
800-514: The multiplexing function is moved as close to the end user as possible, usually into cabinets at the roadside in residential areas, or into large business premises. These aggregated circuits 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 use synchronous optical transmission, for example, SONET and Synchronous Digital Hierarchy (SDH) technologies, although some parts still use
832-445: The next signal can be sent. Most forms of R2 register signaling are compelled, while R1 multi-frequency signaling is not. The term is only relevant in the case of signaling systems that use discrete signals (e.g. a combination of tones to denote one digit), as opposed to signaling systems which are message-oriented (such as SS7 and ISDN Q.931) where each message is able to convey multiple items of formation (e.g. multiple digits of
864-467: The number of personnel required to deliver a specific level of service. In the 1970s, the telecommunications industry began implementing packet-switched network data services using the X.25 protocol transported over much of the end-to-end equipment as was already in use in the PSTN. These became known as public data networks , or public switched data networks. In the 1980s, the industry began planning for digital services assuming they would follow much
896-499: The older PDH technology. The access network defines a number of reference points. 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 standardized in ETSI areas as the V5 interface . Voice quality in PSTN networks was used as
928-437: The prices charged between the operators to carry each other's traffic . In the United Kingdom, the copper POTS and ISDN-based PSTN is being retired in favour of SIP telephony , with an original completion date of December 2025, although this has now been put back to January 2027. See United Kingdom PSTN switch-off . Voice telephony will continue to follow the E.163 and E.164 standards, as with current mobile telephony, with
960-536: The same pattern as voice services and conceived end-to-end circuit-switched services, known as the Broadband Integrated Services Digital Network (B-ISDN). The B-ISDN vision was overtaken by the disruptive technology of the Internet . At the turn of the 21st century, the oldest parts of the telephone network still used analog baseband technology to deliver audio-frequency connectivity over
992-434: The standard for signaling among exchanges internationally. In the mid-20th century, supervision signals on long-distance trunks in North America were primarily in-band, for example at 2600 Hz , necessitating a notch filter to prevent interference. Late in the century, all supervisory signals had been moved out of band. With the advent of digital trunks , supervision signals are carried by robbed bits or other bits in
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1024-476: Was that the telephone exchanges are arranged into hierarchies, so that if a call cannot be handled in a local cluster, it is passed to one higher up for onward routing. This reduced the number of connecting trunks required between operators over long distances, and also kept local traffic separate. Modern technologies have brought simplifications Most automated telephone exchanges use digital switching rather than mechanical or analog switching. The trunks connecting
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