STANDARDIZATION TIMELINE

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ITU standards have played a vital part in shaping the information and communication technologies (ICT) and services of today. As of June 2006, there were 3145 ITU–T Recommendations (standards) in force. This work has rapidly gained pace in recent years. In 2005, for example, 62 new Recommendations were approved, 89 revised and 101 amended. Here, we highlight just some of the main achievements in standardization, as well as some key moments in CCITT/ITU-T history.

Siemens


Note — The year next to each item is when the standard was first approved. Several have since been updated, revised or superseded.

1956	The creation of CCITT
	In the mid-twentieth century, telephony and telegraphy were using the same transmission channels, wires, cables and radio circuits. Therefore, in 1956, ITU decided to merge its International Telephone Consultative Committee, set up in 1924, and the International Telegraph Consultative Committee, established in 1925. They became the International Telegraph and Telephone Consultative Committee (CCITT, from its French title), comprising study groups whose work was conducted in four-year cycles in line with Plenary Assemblies.
1958	International telegrams
	Recommendations for telegraph operational and tariff matters were approved at a special CCITT Plenary Assembly in 1958. These referred to transmission rules, transmission of international telegrams, the gentex service, determination of terminal rates in the European system, and rules for phototelegraphy over circuits normally used for telephone traffic.
1960	Cooperation with other organizations
	The second CCITT Plenary Assembly, in New Delhi, India, approved Resolution No.8 on cooperation with the International Electrotechnical Commission (IEC) in the standardization of cables, wires and waveguides. This decision marked the first example of formal cooperation with an external body. In 1984, the CCITT Assembly’s Resolution 7 became the cornerstone for collaboration with IEC and the International Organization for Standardization (ISO).
1964	International telephone numbering plan
	Between 1960 and 1964, CCITT researched all aspects of intercontinental connection by submarine cable, and evolved numbering and routing plans in anticipation of worldwide automatic telephony and telex services. This led to the approval in 1964 of Recommendations such as E.29 “Numbering for international work.” International telephone numbering plans defined by ITU–T have governed country codes, area codes, and local numbering ever since.
1968	The fax goes global
	The fourth CCITT Plenary Assembly, held in Argentina, approved the first international standards for facsimile machines. Known as “Group 1” standards, they helped the fax to go global. It took six minutes to transmit an A4 page. In 1972, “Group 2” standards were adopted for facsimile machines. It now took three minutes to transmit a page, with a vertical resolution of 100 scan lines per inch. In 1980, a standard was agreed for “Group 3” fax machines, which used digital transmission techniques and took less than one minute per page with a resolution of 200 lines per inch. The mid-1980s explosion in the use of fax technology was in part fuelled by ITU’s fax standards allowing interoperability between devices.

Organizing phone numbers and calls
A telephone numbering plan is a system defined by ITU that allows people to make and receive telephone calls across long distances and national borders. It governs the country codes, area codes, and local numbering for all phone numbers, around the world. In the process of setting up and clearing calls, automatic telephone exchanges must be able to communicate with one another. This is achieved by signalling systems that are also devised by ITU and, for international communications, signalling standards are particularly important.


1969	Improved mobile telephone service
	A precursor of today’s mobile telephony systems was the improved mobile telephone service (IMTS), introduced in 1969. Known by some as “0G” (as opposed to third-generation, 3G) the pre-cellular VHF/UHF radio system linked to the public switched telephone network (PSTN). IMTS was the radiotelephone equivalent of land dial phone service. It was introduced as a replacement to mobile telephone service (MTS) and improved on most MTS systems by offering direct-dial rather than connections through an operator.
1976	Packet switched networks
	Recommendation X.25 was used to provide the first international and commercial packet switching network, the international packet switched service (IPSS). X.25 is a suite of influential ITU–T standard for wide-area networks (WAN). Packet switched networks enjoyed large coverage throughout the world in the 1980s and 1990s before being largely supplanted by newer technologies, such as ISDN, asymmetric digital subscriber line (ADSL), and the internet protocol (IP).
1981	Signalling System 7
	Signalling System 7 (SS7) was approved in 1981 in the Q.7XX-series of Recommendations. Before its implementation, not all nations were party to standards agreements on handling international telephone calls. SS7 paved the way for efficient operation of international networks. SS7 moved to a system in which the signalling information was out-of-band, carried in a separate signalling channel. This avoided the security problems of earlier systems. SS7 is also important in linking voice over internet protocol (VoIP) traffic to the PSTN, and it supports intelligent network (IN) services.
1984	ISDN appears
	Integrated services digital network (ISDN) became the international communications standard for allowing voice and data to be transmitted simultaneously across the world, using end-to-end digital connectivity. It supports data transfer rates of 64 kbit/s. Work on this first, fully digital, circuit-switched telephone system started in 1984. A family of Recommendations (I-series) was developed which provided principles and guidelines on the ISDN concept, as well as detailed specifications of the interfaces between users and networks.
1984	Abstract Syntax Notation 1
	Abstract Syntax Notation 1 (ASN.1) is an extremely important part of today’s networks. ASN.1 is used, for example, in the Signalling System 7 behind most telephone calls; in package tracking, credit card verification and digital certificates, as well as in many of the most popular software programs. ASN.1 is a formal language or notation that describes data structures for representing, encoding, transmitting, and decoding data. It provides a set of formal rules for describing the structure of objects that are independent of machine-specific encoding techniques, and is a precise, formal notation that removes ambiguities.

The transition to digital
During the late 1970s and early 1980s, telecommunications saw a revolutionary shift to digital technologies. Computers and communications became bound together. Long-distance communications became much cheaper as capacity increased via submarine cables and satellites, and there was important progress in public-switched data networks and other areas. One of the most important changes was the move from separately demarcated services to an integrated digital network — known as the integrated services digital network (ISDN). Amid this revolution, ITU’s standardization work was crucial.

1986	JPEG
	The Joint Photographic Expert Group (JPEG) was founded in 1986 by ITU, ISO and IEC to establish a standard for the sequential progressive encoding of continuous tone grayscale and colour images. The JPEG standard is a widely used format for storing and transmitting images online, in digital photography and in many other image compression applications.
1988	IMSI codes used in SIM cards
	ITU–T Recommendation E.212 describes a system to identify mobile devices as they move from network to network. International mobile subscriber identity (IMSI) is a critical part of the modern mobile telecommunication system, allowing a roaming mobile terminal to be identified in another network and for querying of the home network for subscription and billing information.
1988	Public key infrastructure
	A key reference for security standards in use today, Recommendation X.509 provides electronic authentication over public networks. It is a cornerstone for designing applications related to public key infrastructure (PKI), and is used in a wide range of applications, from securing the connection between a browser and a server on the web, to providing digital signatures that enable e-commerce transactions to be conducted with confidence. Without wide acceptance of X.509, the rapid rise of e-commerce would have been impossible.
1988	Audio coding
	The speech communication technology most in use today — PSTN — uses speech coding standards developed by ITU–T (G.711 and the G.72x series). The latest codecs, developed in the 1990s, are used in most VoIP deployments.
1988	Telecommunications Management Network
	The Telecommunications Management Network (TMN) provides a framework to support the management and deployment of telecommunication services. Methods are defined for managing networks using object-oriented principles, and standard interfaces facilitate communication between management entities. Interoperability is a key aspect of TMN-compliant networks. It is used by many of the world’s largest telecommunication carriers.
1989	Digital information over optical fibre
	In 1989, CCITT issued synchronous digital hierarchy (SDH) standards (G.707–G.803) for synchronous data transmission over fibre-optic networks. These are employed in a significant portion of the telecommunication backbone. Carriers’ use of synchronous digital transmission in their backbone fibre-optic and radio networks put in place the enabling technology for many, new broadband data services. It not only brought about high-speed gigabit networks, but also simplified access, bringing the full benefits of software control in the form of flexibility and introduction of network management.

The internet and broadband
Many ITU standards improve internet access and speeds, beginning with the V-series for computer modems which provided most people with their first online experience. Other examples are the SDH standard for the synchronous transmission of data over optical fibre, much used in backbone networks for broadband data services, and the standards for digital subscriber line (DSL) technologies. Also, ITU standards for image and video coding; public key infrastructure (PKI), and voice over IP (VoIP) have significantly shaped our online lives.


1993	The birth of ITU–T
	The additional ITU Plenipotentiary Conference in 1992 adopted structural reforms to give the Union more flexibility to adapt to an increasingly complex environment. In 1993, the new Telecommunication Standardization Sector (ITU–T) was formed, encompassing CCITT and standards-setting activities for wireless systems previously carried out by the former International Radio Consultative Committee (CCIR). The Telecommunication Standardization Advisory Group (TSAG) was also established in 1993.
1993	Digital subscriber line (DSL)
	1993 saw the first standardization of digital subscriber line (DSL) technology. ADSL, defined in the ITU–T G.992 series of Recommendations, used the discrete multi-tone technique (DMT) to allow a greater variety of services to be provided over traditional copper-based telephony networks. DSL meant that copper cable systems owned by incumbent telecommunication companies were given an extended lease of life, while bringing higher bandwidth to small businesses and residential customers. DSL is still the number-one choice for broadband technology.
1996	International freephone numbers
	The first international standard for universal international freephone numbers (UIFN) were adopted in 1996. A UIFN means that a marketer can use the same number throughout the world, allowing customers to make free calls while the company picks up the bill. There are currently over 29 000 UIFNs in service.
1996	Helping to deliver VoIP
	H.323 facilitates the delivery of voice, video and data over computer networks, such as the internet, and remains the most used standard for this job. The H.323 family of standards has been crucial in fostering the development of new VoIP services, winning widespread support from equipment vendors because of the interoperability that it enables. It is estimated that systems using H.323 carry billions of voice minutes each month.
1996	Passive optical networks
	Passive optical network (PON) technology was standardized (G.983.1, G.984.1/2) during the period 1996–2006. PONs are an effective way of implementing optical fibre connections to homes and businesses, and a crucial step towards all-optical networks. PON technology is used in the local loop to connect end-users’ premises in an all-fibre network. By eliminating the dependence on expensive, active network elements, PON enables carriers to make significant savings. The most recent standard, G.984 (GPON), represents a significant boost in total bandwidth and bandwidth efficiency, through the use of larger, variable-length packets. A GPON network delivers up to 2488 Mbit/s of downstream bandwidth, and 1244 Mbit/s upstream.

Next-generation networks
The term next-generation networks (NGN) refers to the move from circuit switched to packet-based networks that many operators worldwide will undertake over the next few years. It will mean reduced costs for service providers, who will also be able to offer a richer variety of services. In 2004, work on NGN standards found a home at ITU following intense industry debate. ITU–T created a Focus Group that went on to produce global standards for NGN.


1996	Asynchronous transfer mode (ATM)
	ATM is a network transport technology based on transferring data in cells (fixed-size packets) and is applicable from low to high data rates. It is a key broadband enabler that is widely used. Many ADSL implementations use ATM as a layer technology, and the technology offers flexible high bandwidths (hundreds of megabits per second), performance measurement and quality of service (QoS) features that are useful for point-to-point and multipoint applications.
1997	New international telephone numbering plan
	In 1997, “The international public telecommunication numbering plan” (E.164) was approved for numbers worldwide. It provides the structure and functionality for the four categories of numbers used for international public telecommunication: geographic areas, global services, networks, and groups of countries. The standard is essential for today’s public phone networks, and without E.164 we would not be able to easily communicate internationally.
1998	Dial-up modems
	Without ITU–T’s modem standards, the internet might not be as widespread as it is. Anyone accessing the internet before the advent of ISDN or broadband technologies would have used a modem built according to ITU specifications. If proprietary standards had been adopted, the internet’s development might have been far more fragmented. Even today, modems remain a very important way of accessing the internet. In 1998, the V.90 standard appeared for the new generation of 56 kbit/s dial-up modems. Work on the V.92 standard began in 1999, and it was approved in 2000. It achieved a two-fold improvement for incoming data speeds.
1998	Broadband access by cable
	Cable is an increasingly common means of accessing broadband services. If you have a cable modem, chances are that it was built according to specifications from ITU–T. The J.112 standard for interactive cable television services was approved in 1998. It fixes modulation protocols for high-speed, bi-directional data transmissions, allowing the transfer of IP traffic over all-coaxial or hybrid fibre/coaxial networks. Recommendation J.117, approved in 1999, covers the connection of cable television feeds into digital television sets. This can be used in high-definition television (HDTV) and conventional sets, anywhere in the world, as well as for terrestrial and satellite television feeds. It allows for the passage of large amounts of data at 200 million bit/s, which is important for digital video and data services.
1998	Harmonizing interconnection rates
	Interconnection rates are what service providers pay when linking networks to exchange traffic. This work has become increasingly complex with market liberalization and globalization. In order to cope with this paradigm shift, ITU–T developed principles for negotiating rates, and measures to help developing countries adjust to the changing market (Recommendation D.140). It also introduced a new concept of international remuneration, moving from an accounting rate system to a termination rate system (Recommendation D.150).

Cybersecurity
Standardization is an effective way of coordinating resources to boost cybersecurity against such threats as phishing, identity theft or spam. All 13 study groups of ITU–T examine security-related questions, and workshops are held with other standards - development organizations. There are over seventy ITU–T Recommendations focusing on cybersecurity, such as X .805, which gives telecommunication network operators and enterprises the ability to provide an end-to - end architecture description from a security perspective. Key players from industry and governments defined the specifications that allow operators to pinpoint all vulnerable points in a network and mitigate them. Incorporating X .805 into a risk-management policy can give network owners the confidence to say that they have addressed security issues to the best of their ability.

2000	Bearer independent call control (BICC)
	BICC protocols were a historic step towards packet based and broadband multimedia networks, enabling the seamless migration of circuit-switched to packet based high-capacity broadband multimedia networks. BICC signaling protocols are used to support legacy PSTN/ISDN services over packet based (IP or broadband) backbone networks, without interfering with interfaces to the existing networks and end-to-end services.
2002	Advanced video coding
	The H.264/AVC video coding standard, approved in 2002, is the first truly scalable video codec, delivering high quality across the entire bandwidth spectrum — from HDTV to videoconferencing and 3G mobile multimedia. In addition to the potential of better image quality, the improved data compression offered by H.264 gives advantages in terms of bandwidth usage (more channels over existing systems) or greater media storage (more video files on media such as DVDs.) Many application areas are likely to benefit from the standard, and it is already deployed in products from major companies.
2006	VDSL 2
	The ITU–T Recommendation for very-high-bit-rate digital subscriber line 2 (VDSL2) was published in 2006. It allows operators to compete with cable and satellite providers by offering services such as high-definition television (HDTV), video-on-demand, videoconferencing, high speed internet access and advanced voice services such as VoIP, over a standard copper telephone cable. The new VDSL2 standard delivers up to 100 Mbit/s both up and downstream, a ten-fold increase over ADSL. By doing so, it provides for so-called fibre-extension, bringing fibre-like bandwidth to premises not directly connected to the fibre-optic segment of a telecommunication company’s network.