Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval (VBI) area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control. Teletext was uni-directional: the user could only receive, and not respond or send data of their own.
Teletext was created in the United Kingdom in the early 1970s by John Adams, Philips' lead designer for video display units to provide closed captioning to television shows for the hearing impaired. Public teletext information services were introduced by major broadcasters in the UK, starting with the BBC's Ceefax service in 1974. It offered a range of text-based information, typically including news, weather and TV schedules. Similar systems were subsequently introduced by other television broadcasters in various countries, with launches in West Germany (ARD and ZDF's Videotext) and the Netherlands (NOS's Teletekst) in 1980.
Teletext formed the basis for the World System Teletext standard (CCIR Teletext System B), an extended version of the original system. This standard saw widespread use across Europe starting in the 1980s, with almost all television sets including a decoder. Other standards were developed around the world, notably NABTS (CCIR Teletext System C) in the United States, Antiope (CCIR Teletext System A) in France and JTES (CCIR Teletext System D) in Japan, but these were never as popular as their European counterpart and most closed by the early 1990s.
Teletext inspired the later Videotex system that enabled bi-directional communication in a format later recognised as a prototype of the World Wide Web (WWW). Implementations included the French Minitel and the British Prestel. Introduced by the General Post Office, Prestel used Teletext's display standards but instead ran over bi-directional telephone lines using modems.
Most European teletext services continued to exist in one form or another until well into the 2000s when the expansion of the Internet precipitated a closure of some of them. However, many European television stations continue to provide teletext services and even make teletext content available via web and dedicated apps. The recent availability of digital television has led to more advanced systems being provided that perform the same task, such as MHEG-5 and Multimedia Home Platform. History
Teletext is a means of sending text and simple geometric shapes to a properly equipped television screen by use of one of the "vertical blanking interval" lines that together form the dark band dividing pictures horizontally on the television screen. Transmitting and displaying subtitles was relatively easy. It requires limited bandwidth; at a rate of perhaps a few words per second. However, it was found that by combining even a slow data rate with a suitable memory, whole pages of information could be sent and stored on the TV for later recall.
In the early 1970s, work was in progress in Britain to develop such a system. The goal was to provide UK rural homes with electronic hardware that could download pages of up-to-date news, reports, facts and figures targeting UK agriculture. The original idea was the brainchild of Philips (CAL) Laboratories in 1970.
In 1971, CAL engineer John Adams created a design and proposal for UK broadcasters. His configuration contained all the fundamental elements of classic teletext including pages of 24 rows with 40 characters each, page selection, sub-pages of information and vertical blanking interval data transmission. A major objective for Adams during the concept development stage was to make teletext affordable to the home user. In reality, there was no scope to make an economic teletext system with 1971 technology. However, as the low cost was essential to the project's long-term success, this obstacle had to be overcome.
Meanwhile, the General Post Office (GPO), whose telecommunications division later became British Telecom, had been researching a similar concept since the late 1960s, known as Viewdata. Unlike Teledata, a one-way service carried in the existing TV signal, Viewdata was a two-way system using telephones. Since the Post Office owned the telephones, this was considered to be an excellent way to drive more customers to use the phones.
In 1972, the BBC demonstrated its system, now known as Ceefax ("seeing facts", the departmental stationery used the "Cx" logo), on various news shows; this was not actual broadcast teletext but was transmitted using a wired connection. The Independent Television Authority (ITA) announced its own service in 1973, known as ORACLE (Optional Reception of Announcements by Coded Line Electronics). Not to be outdone, the GPO immediately announced a 1200/75 baud videotext service under the name Prestel (this system was based on teletext protocols, but telephone-based).
The TV-broadcast based systems were originally incompatible; Ceefax displayed pages of 24 lines with 32 characters each, while ORACLE offered pages of 22 lines with 40 characters each. In other ways the standards overlapped; for instance, both used 7-bit ASCII characters and other basic details. In 1974, all the services agreed on a standard for displaying the information. The display would be a simple grid of text, with some graphics characters for constructing simple graphics. The standard did not define the delivery system, so both Viewdata-like and Teledata-like services could at least share the TV-side hardware (which at that time was quite expensive).
Rollout in the United Kingdom
The world's first demonstration of live broadcast teletext was a 50-page experimental transmission of ORACLE from the Crystal Palace transmitter to an invited audience on 9 April 1973.
The BBC began occasional test transmissions of Ceefax using dummy pages in 1973-4, and by June 1974 it had requested government authorisation to begin formal testing. Approval was granted and the BBC news department put together an editorial team of nine, led by editor Colin McIntyre, to develop a news and information service which began on 23 September 1974. Initially limited to 30 pages, Ceefax expanded to 50 pages in early 1975 and was expected to grow to a "full magazine" of 100 pages later that year.
Despite having been demonstrated first, ORACLE did not begin an experimental service until 30 June 1975.
There was no industrial commitment to make consumer decoders until May 1975, when the UK arm of Texas Instruments was announced as the first company to build decoders that would be sold to TV manufacturers for incorporation into their own sets by early 1976.
Before that point, the only existing teletext decoders were custom-built standalone experimental units, although there was enough technical information about the spec publicly available that the BBC acknowledged in late June 1974 that "a few gifted amateurs" had built their own.
Wireless World magazine ran a series of articles between November 1975 and June 1976 describing the design and construction of a teletext decoder using mainly TTL devices; however, development was limited until the first TV sets with built-in decoders started appearing in 1976.
By May 1976, volume production of teletext TVs had not yet started and while a handful of sets with teletext decoders were on sale, they cost about £1000 each (£11,350 in 2026). To try and reduce the cost of entry for consumers, the manufacturer Labgear produced a prototype standalone decoder box that could be used with any existing 625-line TV set, with an expected price point of £200 (£2260 in 2026), but this was still too expensive to prompt widespread adoption.
By August 1977, it was estimated that up to 3000 teletext TVs had been sold, and both Ceefax and ORACLE were still officially considered "experimental" services. Neither service ever received a formal public launch to separate their experimental phase from full operation; the word "experimental" was simply dropped from references to them in the late 70s.
From October 1977 to April 1978, an industrial dispute meant that ORACLE was blacked out nationally. From 1975 until 1977, ORACLE had operated for 12.5 hours a day Monday to Friday. A planned extension of its operating hours to cover the weekend prompted engineering staff at LWT, the national origination point for ORACLE, to request more money for the additional duties; this was refused, which led to the affected staff refusing to maintain the equipment during the week. A test page was broadcast instead.
By December 1979, it was estimated that there were about 14,000 teletext TVs in use, and that was the first year that the Queen's Christmas speech was publicly announced as being subtitled on Ceefax.
The "Broadcast Teletext Specification" was published in September 1976 jointly by the IBA, the BBC and the British Radio Equipment Manufacturers' Association. The new standard also made the term "teletext" generic, describing any such system. The standard was internationalised as World System Teletext (WST) by CCIR.
Other systems entered commercial service, like Prestel in 1979.
Teletext became popular in the United Kingdom when Ceefax, Oracle and the British government promoted teletext through a massive campaign in 1981.
By 1982, there were two million such sets, and by the mid-1980s they were available as an option for almost every European TV set, typically by means of a plug-in circuit board. It took another decade before the decoders became a standard feature on almost all sets with a screen size above 15 inches (Teletext is still usually only an option for smaller "portable" sets). From the mid-1980s, both Ceefax and ORACLE were broadcasting several hundred pages on every channel, slowly changing them throughout the day.
In 1986, WST was formalised as an international standard as CCIR Teletext System B. It was also adopted in many other European countries.
Development in other countries
A number of similar teletext services were developed in other countries, some of which attempted to address the limitations of the initial British-developed system, by adding extended character sets or improving graphic abilities. For example, state-owned RAI launched its teletext service, called Televideo, in 1984, with support for Latin character set. Mediaset, the main commercial broadcaster, launched its Mediavideo Teletext in 1993. La7Video in 2001, heir to TMCvideo, the teletext of TMC Telemontecarlo born in the mids 90s. Always in the 90s, Rete A and Rete Mia teletexts arrived. Retemia's teletext has not been functional since 2000, Rete A's since 2006, La7Video since 2014 and Mediavideo since 2022. These developments are covered by the different World System Teletext Levels.
In France, where the SECAM standard is used in television broadcasting, a teletext system was developed in the late 1970s under the name Antiope. It had a higher data rate and was capable of dynamic page sizes, allowing more sophisticated graphics. It was phased out in favour of World System Teletext in 1991.
In North America, NABTS, the North American Broadcast Teletext Specification, was developed to encoding NAPLPS teletext pages, as well as other types of digital data. NABTS was the standard used for both CBS's ExtraVision and NBC's NBC Teletext services in the mid-1980s.
Japan developed its own JTES teletext system with support for Chinese, Katakana and Hiragana characters. Broadcasts started in 1983 by NHK.
In 1986, the four existing teletext systems were adopted into the international standard CCIR 653 (now ITU-R BT.653) as CCIR Teletext System A (Antiope), B (World System Teletext), C (NABTS) and D (JTES).