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Teletex was ITU-T specification F.200 [1] for a text and document communications service that could be provided over telephone lines. It was rapidly superseded by e-mail but the name Teletex lives on in several of the X.500 standard attributes used in Lightweight Directory Access Protocol.
Teletex was designed as an upgrade to the conventional telex service. The terminal-to-terminal communication service of telex would be turned into an office-to-office document transmission system by teletex. Teletex envisaged direct communication between electronic typewriters, word processors and personal computers. These units had storage for transmitting and receiving messages. The use of such equipment considerably enhanced the character set available for document preparation.
In addition to the standard character set, a rich set of graphic symbols and a comprehensive set of control characters were supported in teletex. The set of control characters helped in preparation and reproduction of documents. In particular, they permitted the positioning of the printing element, specification of page orientation, left and right margins, vertical spacing and the use of underlining. The page control feature allowed standard A4 size papers to be used for receiving messages instead of the continuous stationery used in conventional telex systems.
A background/foreground operation was envisaged in teletex. Transmission/reception of messages should proceed in the background without affecting the work which the user might be carrying out in the foreground with the equipment. In other words, a user might be preparing a new document, while another document was being transmitted or received. The teletex would also maintain compatibility with the present telex system and inter-operate with it. Telex procedures called for the exchange of header information before the actual document transfer took place. The header information consisted of four parts:
Twenty four characters were used for source/destination ids, 14 characters for date and time stamp, and 7 characters for document reference which also specified the number of pages in the document. Destination/source ID consisted of four fields:
The number of characters allotted to each of the above fields was variable, subject to a maximum for each field, the total being 24 characters.
Electronic mail is a method of transmitting and receiving messages using electronic devices. It was conceived in the late–20th century as the digital version of, or counterpart to, mail. Email is a ubiquitous and very widely used communication medium; in current use, an email address is often treated as a basic and necessary part of many processes in business, commerce, government, education, entertainment, and other spheres of daily life in most countries.
Fax, sometimes called telecopying or telefax, is the telephonic transmission of scanned printed material, normally to a telephone number connected to a printer or other output device. The original document is scanned with a fax machine, which processes the contents as a single fixed graphic image, converting it into a bitmap, and then transmitting it through the telephone system in the form of audio-frequency tones. The receiving fax machine interprets the tones and reconstructs the image, printing a paper copy. Early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines transmit an audio-encoded digital representation of the page, using data compression to more quickly transmit areas that are all-white or all-black.
General Packet Radio Service (GPRS), also called 2.5G, is a packet oriented mobile data standard on the 2G cellular communication network's global system for mobile communications (GSM). GPRS was established by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).
Multipurpose Internet Mail Extensions (MIME) is an Internet standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs. Message bodies may consist of multiple parts, and header information may be specified in non-ASCII character sets. Email messages with MIME formatting are typically transmitted with standard protocols, such as the Simple Mail Transfer Protocol (SMTP), the Post Office Protocol (POP), and the Internet Message Access Protocol (IMAP).
The Open Systems Interconnection model is a conceptual model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection." In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.
Short Message/Messaging Service, commonly abbreviated as SMS, is a text messaging service component of most telephone, Internet and mobile device systems. It uses standardized communication protocols that let mobile devices exchange short text messages. An intermediary service can facilitate a text-to-voice conversion to be sent to landlines.
SOAP is a messaging protocol specification for exchanging structured information in the implementation of web services in computer networks. It uses XML Information Set for its message format, and relies on application layer protocols, most often Hypertext Transfer Protocol (HTTP), although some legacy systems communicate over Simple Mail Transfer Protocol (SMTP), for message negotiation and transmission.
The Transmission Control Protocol (TCP) is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered, and error-checked delivery of a stream of octets (bytes) between applications running on hosts communicating via an IP network. Major internet applications such as the World Wide Web, email, remote administration, and file transfer rely on TCP, which is part of the Transport Layer of the TCP/IP suite. SSL/TLS often runs on top of TCP.
In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths.
In telecommunications and computer networking, a network packet is a formatted unit of data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the payload. Control information provides data for delivering the payload. Typically, control information is found in packet headers and trailers.
In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end communication services for applications. It provides services such as connection-oriented communication, reliability, flow control, and multiplexing.
A Controller Area Network is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer. It is a message-based protocol, designed originally for multiplex electrical wiring within automobiles to save on copper, but it can also be used in many other contexts. For each device, the data in a frame is transmitted serially but in such a way that if more than one device transmits at the same time, the highest priority device can continue while the others back off. Frames are received by all devices, including by the transmitting device.
Prestel, the brand name for the UK Post Office Telecommunications's Viewdata technology, was an interactive videotex system developed during the late 1970s and commercially launched in 1979. It achieved a maximum of 90,000 subscribers in the UK and was eventually sold by BT in 1994.
The Open Systems Interconnection protocols are a family of information exchange standards developed jointly by the ISO and the ITU-T. The standardization process began in 1977.
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 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. In broad terms, it can be considered as Videotex, a system for the delivery of information to a user in a computer-like format, typically displayed on a television or a dumb terminal, but that designation is usually reserved for systems that provide bi-directional communication, such as Prestel or Minitel.
In aviation, ACARS is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. The protocol was designed by ARINC and deployed in 1978, using the Telex format. More ACARS radio stations were added subsequently by SITA.
ITU-T Recommendation Q.931 is the ITU standard ISDN connection control signalling protocol, forming part of Digital Subscriber Signalling System No. 1. Unlike connectionless systems like UDP, ISDN is connection oriented and uses explicit signalling to manage call state: Q.931. Q.931 typically does not carry user data. Q.931 does not have a direct equivalent in the Internet Protocol stack, but can be compared to SIP. Q.931 does not provide flow control or perform retransmission, since the underlying layers are assumed to be reliable and the circuit-oriented nature of ISDN allocates bandwidth in fixed increments of 64 kbit/s. Amongst other things, Q.931 manages connection setup and breakdown. Like TCP, Q.931 documents both the protocol itself and a protocol state machine.
CANaerospace is a higher layer protocol based on Controller Area Network (CAN) which has been developed by Stock Flight Systems in 1998 for aeronautical applications.
ARQ-M, short for Automatic Repeat reQuest, Multiplex, is a radio telegraphy protocol used to reliably forward telex messages over partially reliable radio links. It is a low-speed system designed to match the performance of landline telex systems and allow those messages to be forwarded over long distances using shortwave radios. The first ARQ-M link was built in the Netherlands, and began exchanging messages with a counterpart in New York in 1947.
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