Telex

The telex network was a public switched network of teleprinters similar to a telephone network, for the purposes of sending text-based messages. Telex was a major method of sending written messages electronically between businesses in the post-World War II period. Its usage went into decline as the fax machine grew in popularity in the 1980s.

The "telex" term refers to the network, not the teleprinters; point-to-point teleprinter systems had been in use long before telex exchanges were built in the 1930s. Teleprinters evolved from telegraph systems, and, like the telegraph, they used binary signals, which means that symbols were represented by the presence or absence of a pre-defined level of electric current. This is significantly different from the analog telephone system, which used varying voltages to represent sound. For this reason, telex exchanges were entirely separate from the telephone system, with their own signalling standards, exchanges and system of "telex numbers" (the counterpart of telephone numbers).

Telex provided the first common medium for international record communications using standard signalling techniques and operating criteria as specified by the International Telecommunication Union. Customers on any telex exchange could deliver messages to any other, around the world. To lower line usage, telex messages were normally first encoded onto paper tape and then read into the line as quickly as possible. The system normally delivered information at 50 baud or approximately 66 words per minute, encoded using the International Telegraph Alphabet No. 2. In the last days of the telex networks, end-user equipment was often replaced by modems and phone lines, reducing the telex network to what was effectively a directory service running on the phone network.

Telex machine ASR-32
A Teletype Model 32 used for Telex service

Development

Puma teleprinter
A late-model British Telecom "Puma" telex machine of the 1980s

Telex began in Germany as a research and development program in 1926 that became an operational teleprinter service in 1933. The service, operated by the Reichspost (Reich postal service)[1] had a speed of 50 baud — approximately 66 words per minute.

Telex service spread within Europe and (particularly after 1945) around the world.[2] By 1978, West Germany, including West Berlin, had 123,298 telex connections. Long before automatic telephony became available, most countries, even in central Africa and Asia, had at least a few high-frequency (shortwave) telex links. Often, government postal and telegraph services (PTTs) initiated these radio links. The most common radio standard, CCITT R.44 had error-corrected retransmitting time-division multiplexing of radio channels. Most impoverished PTTs operated their telex-on-radio (TOR) channels non-stop, to get the maximum value from them.

The cost of TOR equipment has continued to fall. Although the system initially required specialised equipment, as of 2016 many amateur radio operators operate TOR (also known as RTTY) with special software and inexpensive hardware to connect computer sound cards to short-wave radios.[3]

Modern cablegrams or telegrams actually operate over dedicated telex networks, using TOR whenever required.

Telex served as the forerunner of modern fax, email, and text messaging — both technically and stylistically. Abbreviated English (like "CU L8R" for "see you later") as used in texting originated with telex operators exchanging informal messages in real time — they became the first "texters" long before the introduction of mobile phones. Telex users could send the same message to several places around the world at the same time, like email today, using the Western Union InfoMaster Computer. This involved transmitting the message via paper tape to the InfoMaster Computer (dial code 6111) and specifying the destination addresses for the single text. In this way, a single message could be sent to multiple distant Telex and TWX machines as well as delivering the same message to non-Telex and non-TWX subscribers via Western Union Mailgram.

Operation and applications

Telex messages are routed by addressing them to a telex address, e.g., "14910 ERIC S", where 14910 is the subscriber number, ERIC is an abbreviation for the subscriber's name (in this case Telefonaktiebolaget L.M. Ericsson in Sweden) and S is the country code. Solutions also exist for the automatic routing of messages to different telex terminals within a subscriber organization, by using different terminal identities, e.g., "+T148".

A major advantage of telex is that the receipt of the message by the recipient could be confirmed with a high degree of certainty by the "answerback". At the beginning of the message, the sender would transmit a WRU (Who aRe yoU) code, and the recipient machine would automatically initiate a response which was usually encoded in a rotating drum with pegs, much like a music box. The position of the pegs sent an unambiguous identifying code to the sender, so the sender could verify connection to the correct recipient. The WRU code would also be sent at the end of the message, so a correct response would confirm that the connection had remained unbroken during the message transmission. This gave telex a major advantage over group 2 fax which had no inherent error-checking capability.

The usual method of operation was that the message would be prepared off-line, using paper tape. All common telex machines incorporated a 5-hole paper-tape punch and reader. Once the paper tape had been prepared, the message could be transmitted in minimum time. Telex billing was always by connected duration, so minimizing the connected time saved money. However, it was also possible to connect in "real time", where the sender and the recipient could both type on the keyboard and these characters would be immediately printed on the distant machine.

Telex could also be used as a rudimentary but functional carrier of information from one IT system to another, in effect a primitive forerunner of Electronic Data Interchange. The sending IT system would create an output (e.g., an inventory list) on paper tape using a mutually agreed format. The tape would be sent by telex and collected on a corresponding paper tape by the receiver and this tape could then be read into the receiving IT system.

One use of telex circuits, in use until the widescale adoption of X.400 and Internet email, was to facilitate a message handling system, allowing local email systems to exchange messages with other email and telex systems via a central routing operation, or switch. One of the largest such switches was operated by Royal Dutch Shell as recently as 1994, permitting the exchange of messages between a number of IBM Officevision, Digital Equipment Corporation ALL-IN-1 and Microsoft Mail systems. In addition to permitting email to be sent to telex, formal coding conventions adopted in the composition of telex messages enabled automatic routing of telexes to email recipients.

United States

Teletypewriter Exchange Service (TWX)

The Teletypewriter Exchange Service (TWX) was developed by the AT&T Corporation in the United States. It originally transmitted at 45.45 baud or approximately 60 words per minute, using five level Baudot code. AT&T began TWX on November 21, 1931.[4][5] AT&T later developed a second generation of TWX called "four row" that used the 110 baud, using eight level ASCII code. TWX was offered in both "3-row" Baudot and "4-row" ASCII versions up to the late 1970s.

TWX used the public switched telephone network. In addition to having separate area codes (510, 610, 710, 810 and 910) for the TWX service, the TWX lines were also set up with a special Class of Service to prevent connections from POTS to TWX and vice versa.

The code/speed conversion between "3-row" Baudot and "4-row" ASCII TWX service was accomplished using a special Bell "10A/B board" via a live operator. A TWX customer would place a call to the 10A/B board operator for Baudot – ASCII calls, ASCII – Baudot calls and also TWX Conference calls. The code / speed conversion was done by a Western Electric unit that provided this capability. There were multiple code / speed conversion units at each operator position.

AT&T published the trade magazine TWX, related to the Teletypewriter Exchange Service from 1944 to 1952. It published articles that touched upon many aspects of the technology.

Western Union purchased the TWX system from AT&T in January 1969.[6] The TWX system and the special US area codes (510, 710, 810 and 910) continued until 1981, when Western Union completed the conversion to the Western Union Telex II system. Any remaining "3-row" Baudot customers were converted to Western Union Telex service during the period 1979 to 1981. Bell Canada retained area code 610 until 1992; its remaining numbers were moved to non-geographic area code 600.

The modem for this service was the Bell 101 dataset, which is the direct ancestor of the Bell 103 modem that launched computer time-sharing. The 101 was revolutionary because it ran on ordinary unconditioned telephone subscriber lines, allowing the Bell System to run TWX along with POTS on a single public switched telephone network.

Telex II was the name for the TWX network after it was acquired from AT&T by Western Union. It was re-acquired by AT&T in 1990 in the purchase of the Western Union assets that became AT&T EasyLink Services.

Western Union

In 1958, Western Union started to build a telex network in the United States.[7] This telex network started as a satellite exchange located in New York City and expanded to a nationwide network. Western Union chose Siemens & Halske AG,[8] now Siemens AG, and ITT[9] to supply the exchange equipment, provisioned the exchange trunks via the Western Union national microwave system and leased the exchange to customer site facilities from the local telephone company. Teleprinter equipment was originally provided by Siemens & Halske AG[10] and later by Teletype Corporation.[11] Initial direct international telex service was offered by Western Union, via W.U. International, in the summer of 1960 with limited service to London and Paris.[12] In 1962, the major exchanges were located in New York City (1), Chicago (2), San Francisco (3), Kansas City (4) and Atlanta (5).[13] The telex network expanded by adding the final parent exchanges cities of Los Angeles (6), Dallas (7), Philadelphia (8) and Boston (9) starting in 1966.

The telex numbering plan, usually a six-digit number in the United States, was based on the major exchange where the customer's telex machine terminated.[14] For example, all telex customers that terminated in the New York City exchange were assigned a telex number that started with a first digit "1". Further, all Chicago-based customers had telex numbers that started with a first digit of "2". This numbering plan was maintained by Western Union as the telex exchanges proliferated to smaller cities in the United States. The Western Union Telex network was built on three levels of exchanges.[15] The highest level was made up of the nine exchange cities previously mentioned. Each of these cities had the dual capability of terminating telex customer lines and setting up trunk connections to multiple distant telex exchanges. The second level of exchanges, located in large cities such as Buffalo, Cleveland, Miami, Newark, Pittsburgh and Seattle, were similar to the highest level of exchanges in capability of terminating telex customer lines and setting up trunk connections. However, these second level exchanges had a smaller customer line capacity and only had trunk circuits connected to regional cities. The third level of exchanges, located in small to medium-sized cities, could terminate telex customer lines and had a single trunk group running to its parent exchange.

Loop signaling was offered in two different configurations for Western Union Telex in the United States. The first option, sometimes called local or loop service, provided a 60 milliampere loop circuit from the exchange to the customer teleprinter. The second option, sometimes called long distance or polar was used when a 60 milliampere connection could not be achieved, provided a ground return polar circuit using 35 milliamperes on separate send and receive wires. By the 1970s, under pressure from the Bell operating companies wanting to modernize their cable plant and lower the adjacent circuit noise that these telex circuits sometimes caused, Western Union migrated customers to a third option called F1F2. This F1F2 option replaced the DC voltage of the local and long distance options with modems at the exchange and subscriber ends of the telex circuit.

Western Union offered connections from Telex to the AT&T Teletypewriter eXchange (TWX) system in May 1966 via its New York Information Services Computer Center.[16] These connections were limited to those TWX machines that were equipped with automatic answerback capability per CCITT standard.

USA based Telex users could send the same message to several places around the world at the same time, like email today, using the Western Union InfoMaster Computer. This involved transmitting the message via paper tape to the InfoMaster Computer (dial code 6111) and specifying the destination addresses for the single text. In this way, a single message could be sent to multiple distant Telex and TWX machines as well as delivering the same message to non-Telex and non-TWX subscribers via Western Union Mailgram.

International Record Carriers

"International Record Carrier" (IRC) was a term created by the Federal Communications Commission (FCC) in the United States. Bell's original consent agreement limited it to international dial telephony, and the Western Union Telegraph Company had given up its international telegraphic operation in a 1939 bid to monopolize U.S. telegraphy by taking over ITT's Postal, telegraph and telephone service (PTT) business. The result was a de-emphasis on telex in the U.S. and the creation of several international telex and telegraphy companies, collectively called IRCs:

  • Western Union Telegraph Company developed a subsidiary named Western Union Cable System. This company was later renamed as Western Union International (WUI) when it was spun off by Western Union as an independent company. WUI was purchased by MCI Communications (MCI) in 1983 and operated as a subsidiary of MCI International.
  • ITT's "World Communications" division (later known as ITT World Communications) was amalgamated from many smaller companies: Federal Telegraph, All American Cables and Radio, Globe Wireless, and the common carrier division of Mackay Marine. ITT World Communications was purchased by Western Union in 1987.
  • RCA Communications (later known as RCA Global Communications) had specialized in global radiotelegraphic connections. In 1986, it was purchased by MCI International.
  • Before World War I, the Tropical Radiotelegraph Company (later known as Tropical Radio Telecommunications, or TRT) put radio telegraphs on ships for its owner, the United Fruit Company (UFC), to enable them to deliver bananas to the best-paying markets. Communications expanded to UFC's plantations, and were eventually provided to local governments. TRT eventually became the national carrier for many small Central American nations.
  • The French Telegraph Cable Company (later known as FTC Communications, or just FTCC), which was founded in 1871, was owned by French investors and headquartered in the United States; it laid transatlantic cable between the two countries. International telegrams routed via FTCC used routing ID "PQ", the initials of the company's founder, Augustin Pouyer-Quertier (1820–1891).
  • Firestone Rubber developed its own IRC, the Trans-Liberia Radiotelegraph Company, which operated shortwave from Akron, Ohio to the rubber plantations in Liberia.

Bell Telex users had to select which IRC to use, and then append the necessary routing digits. The IRCs converted between TWX and Western Union Telegraph Co. standards.

United Kingdom

Telex began in the UK as an evolution from the 1930s Telex Printergram service, appearing in 1932 on a limited basis. This used the telephone network in conjunction with a Teleprinter 7B and signalling equipment to send a message to another subscriber with a Teleprinter, or to the Central Telegraph Office.

In 1945 as the traffic increased it was decided to have a separate network for Telex traffic and the first manual exchange opened in London. By 1954, the public inland Telex service opened via manually switched exchanges. A number of subscribers were served via automatic sub-centres which used relays and Type 2 uniselectors, acting as concentrators for a manual exchange.

In the late 1950s the decision was made to convert to automatic switching and this was completed by 1961; there were 21 exchanges spread across the country, with one international exchange in London. The equipment used the Strowger system for switching, as was the case for the telephone network. Conversion to Stored Programme Control (SPC) began in 1984 using exchanges made by Canadian Marconi, with the last Strowger exchange closing in 1992. User numbers increased over the following years into the 1990s.

The dominant supplier of the Telex machines was Creed, a division of ITT.

A separate service "Secure Stream 300" (previously Circuit Switched Data Network) was a variant of Telex running at 300 baud, used for telemetry and monitoring purposes by utility companies and banks, among others. This was a high security virtual private wire system with a high degree of resilience through diversely routed dual-path network configurations.

British Telecom stopped offering the Telex service to new customers in 2004 and discontinued the service in 2008, allowing users to transfer to Swiss Telex if they wished to continue to use Telex.

Canada

Canada-wide automatic teleprinter exchange service was introduced by the CPR Telegraph Company and CN Telegraph in July 1957 (the two companies, operated by rivals Canadian National Railway and Canadian Pacific Railway, would join to form CNCP Telecommunications in 1967). This service supplemented the existing international telex service that was put in place in November 1956. Canadian telex customers could connect with nineteen European countries in addition to eighteen Latin American, African, and trans-Pacific countries.[17] The major exchanges were located in Montreal (01), Toronto (02), and Winnipeg (03).[18]

Decline

Telex is still in operation but not in the sense described in the CCITT Blue Book documentation. iTelegram offers "telex" without subscriber telex lines. Individual subscribers can use Deskmail, a legacy Windows program that connects to the iTelegram telex network but this is via IP as the last mile.[19][20] Telex has been mostly superseded by fax, email, and SWIFT, although radiotelex, telex via HF radio, is still used in the maritime industry and is a required element of the Global Maritime Distress and Safety System.

See Worldwide use of telegrams by country for current status in different countries.

See also

References

  1. ^ "Fifty years of telex". Telecommunication Journal. International Telecommunication Union. 51: 35. 1984. Retrieved 2017-05-18. Just over fifty years ago, in October 1933, the Deutsche Reichspost as it was then known, opened the world's first public teleprinter network.
  2. ^ Roemisch, Rudolf (1978). "Siemens EDS System in Service in Europe and Overseas". Siemens Review. Siemens-Schuckertwerke AG. 45 (4): 176. Retrieved 2016-02-04. The inauguration of the first telex service in the world in Germany in 1933 was soon followed by the development of similar networks in several more European countries. However, telex did not enjoy significant and worldwide growth until after 1945. Thanks to the great advantages of the new telex service, above all in overcoming time differences and language problems, telex networks were introduced in quick succession in all parts of the world.
  3. ^ "RTTY Software". The DXZone.
  4. ^ Anton A. Huurdeman (2003). The worldwide history of telecommunications. Wiley. p. 302. ISBN 978-0-471-20505-0.
  5. ^ "Typing From Afar" (PDF).
  6. ^ "WU to Buy AT&T TWX". Western Union News. II (4). January 15, 1969.
  7. ^ Easterlin, Phillip R. (April 1959). "Telex in New York". Western Union Technical Review: 45. ISSN 0096-6452. OCLC 1769771.
  8. ^ Easterlin, Phillip R. (October 1960). "Telex in Private Wire Systems". Western Union Technical Review: 131.
  9. ^ Chin, James S.; Gomerman, Jan J. (July 1966). "CSR4 Exchange". Western Union Technical Review: 142–9.
  10. ^ Smith, Fred W. (October 1960). "European Teleprinters". Western Union Technical Review: 172–4.
  11. ^ Smith, Fred W. (January 1964). "A New Line of Light-duty Teleprinters and ASR Sets". Western Union Technical Review: 18–31.
  12. ^ O’Sullivan, T.J. (July 1963). "TW 56 Concentrator". Western Union Technical Review: 111–2.
  13. ^ Easterlin, Phillip R. (January 1962). "Telex in the U.S.A.". Western Union Technical Review: 2–15.
  14. ^ Jockers, Kenneth M. (July 1966). "Planning Western Union Telex". Western Union Technical Review: 92–95.
  15. ^ Jockers, Kenneth M. (July 1966). "Planning Western Union Telex". Western Union Technical Review: 94 figure 2.
  16. ^ Wernikoff, Sergio (July 1966). "Information Services Computer Center". Western Union Technical Review: 130.
  17. ^ Colombo, C.J. (January 1958). "Telex in Canada". Western Union Technical Review: 21.
  18. ^ Easterlin, Phillip R. (April 1959). "Telex in New York". Western Union Technical Review: 47 figure 4.
  19. ^ "International Telegram® - Answers to some common questions". itelegram.com. 2017. Retrieved 2017-05-18. Western Union closed its telegram service in January, 2006. Western Union is now the fastest way to send money online, and iTelegram is the fastest way to send telegram messages. Western Union's telex/cablegram network, Mailgram® service, and Deskmail/Infomaster services are now a part of International Telegram.
  20. ^ "International Telegram - Send a telegram to Antarctica". itelegram.com. 2017. Retrieved 2017-05-18. Delivery: Service by telex / fax / e-mail or INMARSAT terminal (sender must provide number or address).

Further reading

Belgium in the Eurovision Song Contest 1980

Belgium was represented by synthpop band Telex, with the song '"Euro-Vision", at the 1980 Eurovision Song Contest, which took place on 19 April in The Hague. Telex were the winners of the Belgian national final for the contest, held on 24 February. Synthpop had never previously been tried in a Eurovision final, and the choice of song and group caused much comment, particularly regarding the implied sarcasm directed towards Eurovision in the song's deliberately banal lyrics.

Euro-Vision

"Euro-Vision" was the Belgian entry in the Eurovision Song Contest 1980, performed in French by Telex.

The song was performed nineteenth on the night, following Spain's Trigo Limpio with "Quédate esta noche". At the close of voting, it had received 14 points, placing 17th in a field of 19. The band were moderately pleased with the outcome of the Contest, but for a somewhat unusual reason. At the time lead singer Michel Moers was quoted as saying: "We had hoped to finish last, but Portugal decided otherwise. We got ten points from them and finished on the 19th [sic] spot". In hindsight their participation in the Contest however seems to have served its marketing purposes; some thirty years on "Euro-Vision" still remains one of the band's best-known songs, both in Belgium and internationally.

The song was the first entry ever to mention the Contest by name as part of what is generally agreed to have been a send-up of the whole event (previous entries such as Schmetterlinge's "Boom Boom Boomerang" had parodied the Contest without actually naming it). Further, in contrast to the generally upbeat and lively entries submitted from other entrants, Telex performed from behind synthesisers and in a robotic - somewhat Kraftwerk-esque - manner.

Telex released the song in French and English language versions and the band subsequently re-recorded the track for their first 'greatest hits' compilation More than Distance, also released in 1980, then retitled "Neurovision". Furthermore, in 1993 Telex released their first CD box set, once again with a reference to their Eurovision participation back in 1980; the album was entitled Belgium...One Point.

High and Dry

"High and Dry" is a song by the English alternative rock band Radiohead, released as the first single from their second studio album The Bends (1995). It was released as a double A-side with album opener "Planet Telex". "High and Dry" was released in the UK on 5 March 1995.

Hy-Gain Antennas and Rotators

Hy-Gain (often written "hy-gain") is a manufacturer of antenna and antenna related products for the amateur radio industry. Its best-known products are a line of Yagi antennas and antenna rotators. Hy-Gain used to be owned by Telex Communications, which sold it to MFJ Enterprises in 1999.

ISO 1745

ISO 1745:1975 Information processing – Basic mode control procedures for data communication systems is an early ISO standard defining a Telex-oriented communications protocol that used the non-printable ASCII transmission control characters SOH (Start of Heading), STX (Start of Text), ETX (End of Text), EOT (End of Transmission), ENQ (Enquiry), ACK (Acknowledge), DLE (Data Link Escape), NAK (Negative Acknowledge), SYN (Synchronous Idle), and ETB (End of Transmission Block).

It also defines a serial data format, consisting of a start bit, 7 bit ASCII (least significant bit first), a parity bit (even for asynchronous networks, odd for synchronous networks), and a stop bit.

The text of ISO 1745:1975 is not currently freely available, but the corresponding ECMA version is. The protocol it defines seems to now be little used.

Maritime Mobile Service Identity

A Maritime Mobile Service Identity (MMSI) is a series of nine digits which are sent in digital form over a radio frequency channel in order to uniquely identify ship stations, ship earth stations, coast stations, coast earth stations, and group calls. These identities are formed in such a way that the identity or part thereof can be used by telephone and telex subscribers connected to the general telecommunications network to call ships automatically.

Memorex

Memorex Corp. began as a computer tape producer and expanded to become both a consumer media supplier a major IBM plug compatible peripheral supplier. It was broken up and ceased to exist after 1996 other than as a consumer electronics brand specializing in disk recordable media for CD and DVD drives, flash memory, computer accessories and other electronics.

Navtex

Navtex (Navigational Telex) is an international automated medium frequency direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent maritime safety information (MSI) to ships.

Navtex was developed to provide a low-cost, simple, and automated means of receiving this information aboard ships at sea within approximately 370 km (200 nautical miles) off shore.

There are no user fees associated with receiving navtex broadcasts, as the transmissions are typically transmitted from the National Weather Authority (Italy) or Navy or Coast Guard (as in the US) or national navigation authority (Canada).

Where the messages contain weather forecasts, an abbreviated format very similar to the shipping forecast is used.

Navtex is a component of the International Maritime Organization/International Hydrographic Organization Worldwide Navigation Warning Service (WWNWS). Navtex is also a major element of the Global Maritime Distress Safety System (GMDSS). SOLAS Convention mandated certain classes of vessels must carry navtex, beginning August 1, 1993.

Planet Telex

"Planet Telex" is a song written by Radiohead and is the opening track of their 1995 album The Bends. It was released as a double A-side single with "High and Dry", although receiving far less airplay. Originally known as "Planet Xerox", the title was changed to Telex because Xerox is a trademarked brand name.

"Planet Telex" was the only song written during The Bends' recording session instead of beforehand. It was recorded one night when the band returned to the studio after consuming a great amount of alcohol. Lead singer Thom Yorke did vocals lying down while intoxicated.It is one of the most frequently remixed songs in Radiohead's catalogue. Retrospective reviews have noted that its more atmospheric keyboard-dominated sound, compared to other tracks on The Bends, served as an indication of the band's future sound on albums such as OK Computer and Kid A.

The song is also used by British hip-hop duo Dan le Sac vs Scroobius Pip in their 2008 single "Letter from God to Man"

The opening part of this track was looped and played as background music for the Canadian Broadcasting Corporation's (CBC) TV/radio show Q when it was hosted by Jian Ghomeshi. The music played while the host gave an opening monologue.

Project Cybersyn

Project Cybersyn was a Chilean project from 1971–1973 during the presidency of Salvador Allende aimed at constructing a distributed decision support system to aid in the management of the national economy. The project consisted of four modules: an economic simulator, custom software to check factory performance, an operations room, and a national network of telex machines that were linked to one mainframe computer.Project Cybersyn was based on viable system model theory and a neural network approach to organizational design, and featured innovative technology for its time: it included a network of telex machines (Cybernet) in state-run enterprises that would transmit and receive information with the government in Santiago. Information from the field would be fed into statistical modeling software (Cyberstride) that would monitor production indicators, such as raw material supplies or high rates of worker absenteeism, in "almost" real time, alerting the workers in the first case and, in abnormal situations, if those parameters fell outside acceptable ranges by a very large degree, also the central government. The information would also be input into economic simulation software (CHECO, for CHilean ECOnomic simulator) that the government could use to forecast the possible outcome of economic decisions. Finally, a sophisticated operations room (Opsroom) would provide a space where managers could see relevant economic data, formulate feasible responses to emergencies, and transmit advice and directives to enterprises and factories in alarm situations by using the telex network.

The principal architect of the system was British operations research scientist Stafford Beer, and the system embodied his notions of organisational cybernetics in industrial management. One of its main objectives was to devolve decision-making power within industrial enterprises to their workforce in order to develop self-regulation of factories.

Rachel Kushner

Rachel Kushner (born 1968) is an American writer, known for her novels Telex from Cuba (2008), The Flamethrowers (2013), and The Mars Room (2018). She lives in Los Angeles.

Telecommunications in Italy

Telephones - main lines in use:

20.031 million (2008)

Telephones - mobile cellular:

88.58 million (2008)

Telephone system:

modern, well-developed, fast; fully automated telephone, telex, and data services

domestic:

high-capacity cable and microwave radio relay trunks

international:

satellite earth stations - 3 Intelsat (with a total of 5 antennas - 3 for Atlantic Ocean and 2 for Indian Ocean), 1 Inmarsat (Atlantic Ocean region), and NA Eutelsat; 21 submarine cables.

Radio broadcast stations:

AM about 100, FM about 4,600, shortwave 9 (1998)

Radios:

50.5 million (1997)

Television broadcast stations:

358 (plus 4,728 repeaters) (1995)

Televisions:

30.5 million (1997)

Internet Hosts:

22.152 million (2009)

Internet users:

24.992 million (2008)

Country code (Top-level domain): .it

Telecommunications network

A telecommunications network is a collection of terminal nodes in which links are connected so as to enable telecommunication between the terminals. The transmission links connect the nodes together. The nodes use circuit switching, message switching or packet switching to pass the signal through the correct links and nodes to reach the correct destination terminal.

Each terminal in the network usually has a unique address so messages or connections can be routed to the correct recipients. The collection of addresses in the network is called the address space.

Examples of telecommunications networks are:

computer networks

the Internet

the telephone network

the global Telex network

the aeronautical ACARS network

Telegraphy

Telegraphy is the long-distance transmission of textual messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined and such systems are thus not true telegraphs.

The earliest true telegraph put into widespread use was the optical telegraph of Claude Chappe, invented in the late eighteenth century. The system was extensively used in France, and European countries controlled by France, during the Napoleonic era. The electric telegraph started to replace the optical telegraph in the mid-nineteenth century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initally used mostly as an aid to railway signalling. This was quickly followed by a different system developed in the United States by Samuel Morse. The electric telegraph was slower to develop in France due to the established optical telegraph system, but an electrical telegraph was put into use with a code compatible with the Chappe optical telegraph. The Morse system was adopted as the international standard in 1865, using a modified Morse code developed in Germany.

The heliograph is a telegraph system using reflected sunlight for signalling. It was mainly used in areas where the electrical telegraph had not been established and generally uses the same code. The most extensive heliograph network established was in Arizona and New Mexico during the Apache Wars. The heliograph was standard military equipment as late as World War II. Wireless telegraphy developed in the early twentieth century. Wireless telegraphy became important for maritime use, and was a competitor to electrical telegraphy using submarine telegraph cables in international communications.

Telegrams became a popular means of sending messages once telegraph prices had fallen sufficiently. Traffic was became high enough to spur the development of automated systems – teleprinters and punched tape transmission. These systems led to new telegraph codes, starting with the Baudot code. However, telegrams were never able to compete with the letter post on price, and competition from the telephone, which removed their speed advantage, drove the telegraph into decline from 1920 onwards. The few remaining telegraph applications were largely taken over by alternatives on the internet towards the end of the twentieth century.

Teleprinter

A teleprinter (teletypewriter, Teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initially they were used in telegraphy, which developed in the late 1830s and 1840s as the first use of electrical engineering. The machines were adapted to provide a user interface to early mainframe computers and minicomputers, sending typed data to the computer and printing the response. Some models could also be used to create punched tape for data storage (either from typed input or from data received from a remote source) and to read back such tape for local printing or transmission.

Teleprinters could use a variety of different communication media. These included a simple pair of wires; dedicated non-switched telephone circuits (leased lines); switched networks that operated similarly to the public telephone network (telex); and radio and microwave links (telex-on-radio, or TOR). A teleprinter attached to a modem could also communicate through standard switched public telephone lines. This latter configuration was often used to connect teleprinters to remote computers, particularly in time-sharing environments.

Teleprinters have largely been replaced by fully electronic computer terminals which typically have a computer monitor instead of a printer (though the term "TTY" is still occasionally used to refer to them, such as in Unix systems). Teleprinters are still widely used in the aviation industry (see AFTN and airline teletype system), and variations called Telecommunications Devices for the Deaf (TDDs) are used by the hearing impaired for typed communications over ordinary telephone lines.

Telex (anti-censorship system)

Telex is a research anti-censorship system that would allow users to circumvent a censor without alerting the censor to the act of circumvention. It is not ready for real users, but a proof-of-concept mock system exists.

Telex (band)

Telex was a Belgian synthpop group formed in 1978 by Marc Moulin, Dan Lacksman and Michel Moers, with the intention of "making something really European, different from rock, without guitar — and the idea was electronic music".

Telex (input method)

Telex (Vietnamese: Quốc ngữ điện tín, lit. 'national language telex'), is a convention for encoding Vietnamese text in plain ASCII characters. Originally used for transmitting Vietnamese text over telex systems, it is now a popular input method for computers.

Telex Communications

Telex Communications, originally Telex Corporation, was a Burnsville, Minnesota-based manufacturer of hearing aids and audio equipment. Founded in 1936 as a maker of hearing aids, it entered the computer peripherals businesses in the 1960s. Telex Communications was structured as a subsidiary of Telex Corp in the 1970s. Telex Corp was acquired by Memorex in 1988, which renamed itself Memorex Telex NV. The hearing aid portion of Telex Corp. was subsequently spun out as in 1989 as Telex Communications, an independent company. Memorex retained Telex Corp's peripherals businesses.

In February 1998 Telex Communications merged with Electro-Voice.

In August 2006, the company was acquired by Germany's Bosch Group for $420 million, becoming a business unit under the name "Bosch Communications Systems".One of its chairmen, Roger Wheeler was murdered by the Winter Hill Gang in 1981 at Southern Hills Country Club in Tulsa, Oklahoma.

History
Pioneers
Transmission
media
Network topology
and switching
Multiplexing
Networks

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