International union of telecommunications

The International union of telecommunications (UIT) is the most former technical international organization of coordination, since it was created under the name of International union of the telegraph in 1865.

Its seat is with Geneva in Suisse.

The development of the helping Telephone, it adopts its current name, International union of telecommunications (in English: International Telecommunication Union or ITU) in 1932 and is seen attached directly to the the United Nations in 1947.

The UIT, within which the States and the private sector coordinate themselves, is in charge of the regulation and of the planning of telecommunications in the world, it establishes the Norme S of this sector and disseminates all the technical informations necessary to allow the exploitation of the world services of Télécommunications. Within this framework, it manages also the attribution of the radioelectric wavebands for the hertzian communication (IFRB, “ International Frequency Registration Board ”).

In addition to its general secretary and the IFRB, the UIT are divided into three work groups:

UIT-T (CCITT, “ Telephone and Telegraphic International Advisory committee ”, until 1993): draft technology matters and of standardization. To each category of standards corresponds a letter of the alphabet, the reference of the standard being supplemented of a number. The standards of the series V (Data transmission by the phone network), for example V.24 or V.90, and of series X (open Data-processing networks and systems), for example X.25, X.400 or X.500, are more particularly known users.

UIT-R (CCIR, “ International Advisory committee of the radiocommunications ”, until 1993) milked technology matters and of exploitation concerning the radiocommunications.

UIT-D (BDT, “ Office of Development of Telecommunications ”, until 1993) attempts to promote the access to telecommunications in the countries in the process of development.

Original goal

The international standards produced by the UIT-T are called “ Recommendations ” (with a capital letter in order to make the distinction with the common direction of the word " recommandations"). Like the UIT-T belongs to the UIT, which is an Organization of the the United Nations, its standards have an international range more important than those of the majority of the other organizations publishing of the standards of similar presentation.

History

Historically, of 1960 to the creation of the UIT-T, in 1992, Recommendations of the CCITT were presented every four years to " assemblies pléniaires" for validation, and the whole of Recommendations was published after each assembly pléniaire in a collection of volumes named collectively by the color of their covers. For example, there was the Yellow Livre after the assembly of 1980, the Red book after that of 1984 and the Blue Livre in 1988. These publications were divided into booklets of 700 pages, sold separately. The four years cycle made the CCITT slow and very " délibérateur".

The reorganization of the UIT, the Seventies at the Nineties

The development of the Personal computers, at the beginning of the Années 1980 created a new practice at the professionals and private individuals: adoption of new methods communications which were not yet completely standardized. In fact, the producing organizations of standards have more quickly to develop their standards under penalty of finding itself with standards “de facto” which supplanted the standards " officiels".

Alas, following the example International organization of standardization, the CCITT was too slow to adapt to this new way of doing.

In certain cases, a battle began between several standards owners without there not being truly of winner, as it is still today the case for certain technologies (the FAXES colors, or the JavaScript for example). Sometimes, the public was directed towards organizations perceived like more reactive and more understanding, in particular of the governmental organizations such as the Internet Engineering Task Force (IETF), or of the consortia deprived such as the World Wide Web Consortium (W3C).

Standardizations in “real-time”, of 2000 with today

Like remedy for this situation, the UIT-T works from now on in a more continuous and regular way. Time separating the proposal from a working paper by a company member and its adoption as full and whole Recommandation by the UIT-T can be of a few months, even less. This makes it possible the UIT-T to be more reactive in its answer at the requests of the users, within sight of the fast development of the New technologies. Its quality control and its revisions are more effective than with the old protocol, which extended over four years.

The Policy of update

With the old protocol, a standard which was amended could (with the need) preserve its title of recommendation and its reference. Thus, the networks of the type X.25 (with packet switching) used two different modes of operations, according to whether it were the standard of 1980 (Yellow Book) or of 1984 (Red book) which was implemented. Now, it is usual that the standards are simply marked like " remplacés" when they are revised, functionalities of the previous models not being modified, and new versions while bringing news simply.

Standards can be developed to extend or supplement another standard rather than to replace it. They are then named by adding " bis" or " ter" with the reference of the original standard, as for " v.26bis" and " V.26ter" for example.

List recommendations and standards

The standards and principal recommendations of the UIT-T are:

With - Organization of work of the IUT-T

B - Significance of the expressions: definitions, symbols, classification

C - Statistics generals on telecommunications

D - General principles of tariffing

E - General operations on the networks, the telephone services, the housekeeping operations and the human factors

E.123 Notation for the national and international phone numbers
Plane E.163 of classification for the international telephone service
E.164 the plan of classification for international public telecommunications

Supplement 2 - Portability of the numbers

F - Nontelephone telecommunication services

F.300 Characteristics of the service of Videotex

G - Systems of transmission and media, numerical systems and networks

Often only called G-standards .

G.165 Annuleur of echo
G.703 Characteristic physics and electric of the numerical support treated on a hierarchical basis
G.707 Strucure of node network for the synchronous numerical Hierarchies.
G.709 Structure for the Network with Optical Transport (RTO)
G.711 audio Compression (law $\ mu$ )
G.721 audio Compression ADPCM (replaced by G.726)
G.722 Compression of the voice (widened band)
G.722.1 Compression of the voice (widened band, low flow)
G.722.2 Compression of the voice AMR-WB (widened band, low flow)
G.723.1 Compression of the voice CELP
G.726 audio Compression ADPCM
G.727 audio Compression ADPCM (alternative of G.726)
G.728 Compression of the voice LD-CELP
G.729 Compression of the voice ACELP
G.729.1 Compression of the voice (widened band, low flow)
Numerical G.991.2 Line with Symmetrical Access and High-speed (G. SHDSL)
G.992.1 ADSL (G.DMT)
G.992.2 ADSL (G.Lite)
G.992.3/4 ADSL2
G.992.5 ADSL2+
G.1030 Estimate of end to end performance in the networks IP for the applications of data.
G.1040 Contribution network for the transaction temporal.
G.1050 network model to evaluate the performances of multi-media transmission within the framework of IP

H - Audio-visual systems and multimedia

H.223 Protocol of Multiplexing for the multi-media communication with low flow
H.225.0 Protocol of format of notification of call, media (audio and video), of empaquettage of flow, synchronization of multi-media flow and messages of control. Included in the past RTP
H.235 Description of safety in H.323
H.239 Description of the use of the double flow in the videoconferences, usually: one for the direct one (it video), the remainder for presentations (given texts, etc)
H.245 Protocol of control for the communications multi-media.
H.261 Standard of video compression, circa 1991
H.262 Standard of video compression (common text with the second part of MPEG-2), circa 1994
H.263 Standard of video compression, circa 1995
H.263v2 (a.k.a. H.263+) Standard of video compression, circa 1998
H.264 Standard of video compression (technically aligned with part 10 of MPEG-4), circa 2003
H.320 Equipment of the terminals and System of viso-telephony in the event of narrow band
multi-media H.323 Communication system based on the packages

Appendix D - Simulation of Real-time on the systems H.323
Appendix G - Conversation Text
Appendix J - Safety for the appendix F of H.323
Appendix K - Channel of transport of control of service based on HTTP in H.323
M.1 Appendix - Encapsulation of protocol of notification (Qsig) in H.323
M.2 Appendix - Encapsulation of protocol of notification (Isup) in H.323

Final H.324 for multi-media communication in low flow
H.332 Extension of H.323 for the slightly coupled conferences
H.450 Description of additional services for H.323

I - Integrated services digital network (ISDN)

J - Transmission of television, audio programs and other signals multimedia

K - Protections against the interferences

L - Construction, installation and protection of the cables and other elements of the external installation

M - TMN and maintenance of the networks: systems of international transmission, telephone telephone circuits, telegraph, facsimile and one-way circuits

NR - Maintenance: program audio international and transmission circuits of television

O - Specifications of the measuring instruments

P - Quality of the telephone transmission, installations telephone, networks on local line

Q - Commutation and signal

Q.23 Notification of access in double tone and multifrequency
Q.50 Notifications between the equipment of multiplication of circuit and the international centers of routing
Q.700 Introducion to CCITT System of notification 7 (or SS7)
Q.701 Descritpion functional calculus of the transfers of messages of the System of notification 7 (or SS7)
Q.702 Notification of data link
Q.703 Notification of data
Q.704 Messages and functions of notifications networks
Q.705 Structure of Notifications networks
Q.706 Notification of the Performances of the Transfers of Messages
Q.707 Test and maintenance
Q.708 international Procedure of assignement of code of notifications
Q.709 Reference for the hypothetical notifications of connections
Q.710 Transfer of messages simplified for the small systems
Q.711 functional Description of the Notifications of connection and control
Q.712 Definition and function of the messages of Notifications of connection and control
Q.713 Formats and codes of the Notifications of connection and control
Q.714 Procedures of the Notifications of connection and control
Q.715 User guide of the Notifications of connection and control
Q.716 Performances of the Notifications of connection and control
Q.921 Layer 2 of the standards for the notifications ISDN
Q.931 Layer 3 of the standards for the notifications ISDN
Q.922-A Procedure of connection of access to the services of transport (LAPF)
Q.933 Standard of interworking for the relayage of the frames adopting the majority of the recommendations of RFC 1490

R - Telegraphic transmission

S - Final equipment for the telegraphic services

T - Terminals for the services telematics

T.0 Classification of the telecopiers intended for the transmission of documents on the phototelegraphic public networks
T.1 Standardization of the apparatuses
T.4 Standardization of the telecopiers of Group 3 for the transmission of documents
T.5 Methodology of test of the equipment of treatment of telefax of group 3 on the public phone network commutated

This text was approved and published like Rec. UIT-T G.511, then renumbered T.5 the 2002-02-15 without another modification]]

T.6 Diagrams of coding and functions of ordering of coding of the telefax for the telecopiers of group 4
T.10 Transmission of documents by telefax on circuits of the telephone type rented
T.10bis Transmission of documents by telefax on the public phone network commutated
T.23 Test card color standardized for the transmissions of documents by telefax
T.24 Series standardized of test cards digitized
T.30 Procedures for the transmission of documents by telefax on the network telephone general commutated
T.31 Ordering of a data circuit terminating equipment of telefax in asynchronous mode - Class of service 1
T.32 Ordering of a data circuit terminating equipment of telefax in asynchronous mode - Class of service 2

Roadmap 30.10.1997: Corrigendum

T.33 Routage of the telefaxes by means of under-addresses
T.35 Allotment procedure of the codes defined by the UIT-T for the facilities not standardized
T.36 Capacités of safety to use with the telecopiers Group 3
T.37 Procédures for the transfer of information of telefax in mode differed on Internet network
T.38 Procédures from communication from telefax from Group 3 in real-time on the networks with protocol Internet
T.39 Profils from application for terminals voice and simultaneous telefax
T.42 Méthode of representation of the polychrome half-tones in telefax
T.43 Representations of images semitones polychrome and monochromic using the algorithm of coding without loss for the telefax
T.44 Contained of mixed graphic screen
T.45 Coding of the colors by beaches
T.50 international Alphabet of reference (old international alphabet n°5 or AI5) - information Technologies - Character sets coded with 7 bits for the information exchange
T.51 Latin Character sets coded for services of telematics
T.52 coded Character sets not Latin for the services of telematics
T.53 Functions of order in matters coded for the services of telematics
T.60 final Equipment to use in the service teletex
T.61 Character set and character sets coded for the international service teletex

Ever published. Removed because of suppression of the service Teletex]] T.62]] Procedures of order for the service teletex and the service of telefax of group 4

T.62bis Procedures of order for the services of teletex and telefax of group 4 established on the basis of X.215 Recommendation and X.225
T.63 Checking of the conformity of the terminals teletex
T.64 Procedures of conformance testing for the Recommendations teletex
T.66 Codes of telefax to use within the framework of the V.8 Recommendations and V.8 (a)
T.70 Service of basic transport independent of the network for services of telematics
T.71 Access protocol to the connection balanced (LAPB) wide for a service out of semi-duplex at the physical level
T.80 Component communes for the compression and the communication of images - Basic principles
T.81 Technologies information - numerical Compression and coding of the still images of photographic nature - Regulations and guiding lines
T.82 Technologies information - coded Representation of the images and the sound - progressive Compression of the images into two let us tons
T.83 Technologies information - numerical Compression and coding of the still images to modelled continuous: tests of conformity

This Recommendation comprises 3 diskettes containing the data of test of conformity of the coder and the decoder credits.]] T.84]] information Technologies - numerical Compression and coding of the still images to modelled continuous: extensions

T.85 Profiles of application for the T.82 Recommendation - progressive Compression of the images in two let us tons (diagram of coding JBIG) for the devices of telefax
T.86 Technologies information - numerical Compression and coding of the still images to modelled continuous: recording of profiles JPEG, profiles SPIFF, labels SPIFF, color spaces SPIFF, the APPn markers, the types of compression SPIFF and the organizations of recording (REGAUT)

Roadmap, February 1999: English corrigendum only]] T.87]] information Technologies - Compression without loss and quasi without loss of still images to modelled continuous - Principles This Recommendation comprises a diskette containing the implementation of reference of the system of compression without loss and quasi without loss JPEG-LS as well as a whole of test cards of conformity.]] T.88]] Technologies information - Coding with or without loss of the images to the feature

T.89 Profiles of application for the T.88 Recommendation - Coding with or without losses of the images two let us tons (JBIG2) for the telefax
T.90 Caractéristiques and protocols of the terminals applicable to the services of telematics in the ISDN
T.100 international Echange of information for the interactive Videotex
T.101 international Interfonctionnement for the services Vidéotex
T.102 Protocoles from beginning to end for the syntactic Videotex for the ISDN in mode circuit
T.103 Protocoles from beginning to end for the syntactic Videotex for the ISDN in mode package
T.104 Access in package mode for the syntactic Videotex via the public phone network commutated
T.105 Protocol of application layer for the syntactic Videotex
T.106 Framework of the protocols for terminals Videotex
T.107 Service of man-machine interface improved for the Videotex and other services of consultation
T.120 Protocoles of data for multi-media conference
T.Imp120 Revised Implementor' S Guides for the ITU-T T.120 Recommendation series
generic T.121 Modèle of application
multipoint T.122 Department of communication - Definition of the service
T.123 Piles of protocols data suitable for the network for conferences multimedia
generic T.124 Order of conference
T.125 Specification of the protocol of the multipoint department of communication
T.126 Protocol of the multipoint service of fixed imagery and annotation
T.127 multipoint Protocol of transfer of binary files
T.128 multipoint Division of application
T.134 Entity of conversational application in mode text
T.135 Transactions between system of reservation and users in the conferences T.120
T.136 Protocol of application of order of distant equipment
T.137 Management of the virtual meeting room of order audio-visual of the conferences multimedia
T.140 Protocol of conversation in text mode for multi-media application
T.150 Final of telewriting
T.170 general Framework of the Recommendations of the series T.170
T.171 Protocols for the interactive audio-visual services: coded representation of the multimedia objects and hypermédias
T.172 MHEG-5 - Support of the interactive applications of basic level
T.173 Representation of scripts MHEG-3 for the exchanges
T.174 Application program interface of application for system MHEG-1
T.175 Application program interface of application for system MHEG-5
T.176 Application program interface of application for the ordering and the numerical control of memory support
T.180 homogeneous Mechanism of access to the departments of communication
T.190 co-operative Treatment of the documents - Highlights and basic services
T.191 co-operative Treatment of the documents - Synchronous joint edition (point-to-point)
T.192 co-operative Treatment of the documents - Services complex: synchronous joint edition and presentation/joint examination of documents
T.300 general Principles of the telematic interfunctioning
T.330 telematic Access to the mail systems person to person
T.351 Method for the page layout of telefax of messages in mode character
T.390 Characteristic of the service teletex necessary to the interfunctioning with information the service telex
T.411 Technologies - open Architecture of the documents and interchange format: general introduction and principles
T.412 Technologies information - open Architecture of document and format of transfer: structures of the documents
T.413 Technologies information - open Architecture of document and format of transfer: interface abstracted for handling from documents ODA
T.414 Technologies information - open Architecture of document and format from transfer: profile of document
T.415 Technologies information - open Architecture of document and format of transfer: open format of exchange of the documents
T.416 Technologies information - open Architecture of document (ODA) and format of transfer: structure of contents of the type characters
T.417 Technologies information - open Architecture of document and format of transfer: architectures of dot chart contents
T.418 Technologies information - open Architecture of document and format of transfer: structure of geometrical graphic contents
T.419 Technologies information - open Architecture of document and format of transfer: architectures of audio contents
T.421 Technologies information - open Architecture of document and format of transfer: table structures and tabular page layout information
T.422 Technologies - open Architecture of document and format of transfer: Identification of fragments of document
T.424 Technologies information - open Architecture of document and format of transfer: temporal relations and nonlinear structures
T.431 Transfer and handling of documents - Services and protocols - general Introduction and principles
T.432 Transfer and handling of documents - Services and protocols - Definition of the service
T.433 Transfer and handling of documents - Services and protocols - Specification of protocol
T.434 binary Format of transfer of file for the services telematics
T.435 Transfer and handling of documents - Services and protocols - Definition of the abstract service and procedures for the handling of document with confirmation
T.436 Transfer and handling of documents - Services and protocols - Specification of protocols of handling of documents with confirmation
T.441 Transfer and handling of documents (DTAM) - Structure of exploitation
T.501 Profile of application of document MM for the exchange of documents formatted in mixed mode
T.502 Profile of application of document PM-11 for the transfer of documents to simple and contents characters in forms retraitable and formatted structure
T.503 Profile of application of document for the transfer of documents of telefax of Group 4
T.504 Profile of application of document for the interfunctioning videotex
T.505 Profile of application of document PM-26 for the exchange of documents with mixed contents, of structure improved, in forms retraitable and formatted
T.506 Profile of application of document PM-36 for the exchange of wide documentary structures and documents to mixed contents in forms retraitable and formatted
T.510 Overall picture of the Recommendations of the series T.510
T.521 Profile BT0 of application of communication for the mass transfer of documents on the basis of service of session
T.522 Profile BT1 of application of communication for the mass transfer of documents
T.523 Profile of application of the communication in mode disconnected n° 1 for the interfunctioning videotex
T.541 operational Profile of application for the interfunctioning videotexes
T.561 Characteristic of the terminals for the procedure mixed MM
T.562 Characteristic of the terminals for the mode retraitable teletex PM 1
T.563 Characteristic of the telecopiers of group 4
T.564 Characteristic of the footbridges for the interfunctioning videotexes
T.571 Characteristic of the terminals for the file transfer of telematics in the service teletex
T.611 programmable Interface of communication APPLI/COM for the services of telefax of group 3, of telefax of the group 4, teletex, telex of email and of transfer of file
T.800 Technologies information - System of coding of images JPEG 2000: system of coding core
T.801 Technologies information - System of coding of images JPEG 2000: extensions
T.802 Technologies information - System of coding of images JPEG 2000: animated images JPEG 2000
T.803 Technologies information - System of coding of images JPEG 2000: tests of conformity
T.804 Technologies information - System of coding of image JPEG 2000: knowledge robots
T.807 Technologies information - system of coding of image JPEG 2000: Protected JPEG 2000
T.808 Technologies information - System of coding of images JPEG 2000: tools for interactivity, interfaces of application programs and protocols
T.810 Technologies information - system of coding of image JPEG 2000: Hertzian
T.851 Coding of still images UIT-T T.81 (JPEG-1) using an alternate arithmetic coder
T.870 Technologies information - Compression without loss and quasi without loss of still images to modelled continuous: Extensions
T.Sup1 Specification of the tests of conformity for the Recommendations of the series T.170

U - Telegraphic commutation

V - Data communication on a phone network

V.1 Équivalence enters the notations of binary symbol and the significances of the conditions of a biconditional code.
V.5 Standardization of the flows of synchronous signals of data (600, 1200,2400,4800 and 9600 bps).
V.10 Recommendate (validated for the first time in 1976), for the electrical circuits unbalanced for data communications higher than 100 kbps.
V.11 Recommendate (validated for the first time in 1976), for the electrical circuits balanced for data communications higher than 10 Mbps.
V.17 Protocol for the Fax using the Modulation TCM with flows of 12 and 14.4 kbps.
V.21 Recommendation for communications in full-duplex between two analogical telephone modems using the modulation AFSK with 300 bauds to transport the data to 300 bps.
V.22 Recommendation for communications in full-duplex between two analogical telephone modems using the modulation PSK with 600 bauds to transport the data at 1200 or 600 bps.
V.22bis Extension of V.22 untilisant the modulation QAM to 600 bauds to transport the data at 1200 or 2400 bps, with compatibility with V.22.
V.23 Recommendation for communications in half-duplex between two analogical telephone modems using the modulation FSK to 600 or 1200 bauds to transport digital data to 600 or 1200 bps (respectively). Optional opposite channel with 75 bauds for transport to 75 bps.
V.24 a list of definition for the circuits of exchange between DTE and DCE (validated for the first time in 1964. It is equivalent to part of EIA RS 232: for electric and physical details, to see V.28 and others.
V.25 Recommendation (validated for the first time in 1968), for the equipment of calls and/or automatic answer on the phone lines, uilisant the circuits of exchanges defined in V.24, in particular for the automatic calls in parallels. This included procedures to decontaminate the annuleurs and suppressors of echo of network.
V.25bis Extension of V.25 using the circuit of exchange defined in V.24 for traditional transfers of information. The formats of orders are defined for the operations synchronous or assynchrones and directed characters or bits (HDLC.
V.26 Recommendation (validated for the first time in 1968) for communications in full-duplex between two analogical modems of line hot using the modulation PSK with 1200 bauds for synchronous transport of the data to 2400 bps. Optional opposite channel with 75 bauds for transport to 75 bps in the two directions.
V.26bis Extension of V.26 (validated for the first time in 1972) for communications in half-duplex between two analogical telephone modems, addition of a flow of compatibility of 1200 bps (always with 1200 bauds).
V.26ter Extension of V.26 (validated for the first time in 1972) for communications in full-duplex between two analogical telephone modems for synchronous transport and assynchorne of data with a flow of compatibility of 1200 bps (with 1200 bauds) and separation of the channels by cancellation of echo.
V.27 Recommendation (validated for the first time in 1972) for communications in full-duplex or half-duplex between two analogical modems of line hot using the modulation PSK with 1600 bauds for synchronous transport of the data to 4800 bps. Optional opposite channel with 75 bauds for transport to 75 bps.
V.27bis Extension of V.27 (validated for the first time in 1976), adding a speed of modulation, compatible with V.26, of 1200 bauds to transport the data to 2400 bps. A adaptif equalizer is included to manage the lines low quality.
V.27ter Extension of V.27bis to use with telephone modems.
V.28 Recommendation (validated for the first time in 1972) for the electrical circuits balanced for the data communication. With the specification of circuit of V.24 and the connectors 25 pins (and the assignements of pins of IS 2110, there is a compatibility with EIA RS 232.
V.29 Recommendation (validated for the first time in 1976]] for communications in full-duplex or half-duplex between two analogical modems of line hot using the modulation QAM with 2400 bauds for synchronous transport of the data to 9600 bps. Flows of compatibility of 7200 and 4800 bps with 2400bauds for slowed down modulations. Multiplexing of the secondary canals of 7200,4800 and 2400 bps validates until a whole of 9600 bps in option. A derivative of this standard is used for the transmission of facsimilés (fax).
V.32 Recommendation (validated for the first time in 1984 for a duplex family of communication between analogical telephone modems using the modulation QAM with 2400 bauds to transport the data to 9600,4800 or 2400 bps.
V.32bis Operations for a duplex modem with flows of 14.4 kbps for use on the general phone network and the similar circuits into end to end with 2 cables. Use of a flow of compatibility of 12 kbps. This standard was improved by the manufacturers of modems to create the ad hoc Standard V.terbo, with a flow of 19.2 kbps, was proposed for a standardization as V.32ter, but ever accepted.
V.34 Standard for communications full-duplex going up to 28.8 kbps with compatibility for flows inferior according to the distant modem and quality of the phone line. This standard is also known under the name V.Fast, for the modem " pre-standard" called V.FC (V.FastClass).
V.34 (a) Communication protocol for data communications in full-duplex up to 33.6 kbps between two analogical telephone modems.
V.42 Protocol of correction of errors.
V.42bis Procedures of data compression for the DCE using the procedures of correction of error for assurrer the transfer of information, even for the most parasitized phone lines. Ratified by the CCITT in January 1990.
V.44 Protocol of data compression.
V.90 Recommendation for pairs of analogical and numerical modems for use on the phone network public with flows going up to 56 kbps while going down (with an encoding PCM) and 33.6kbps while going up (with a modulation QAM). V.90 Mode 2 also used PCM for rising flow. This standard is also known under the name V.Fast, for the modem " pre-standard" called V.FC (V.FastClass). Before the arrival of the standard, there were two commercial standards in competition for transmissions with 56kbps while going down: X2 and K56flex. K56flex was itself a fusion between K56 and 56flex.
V.92 Recommendation for pairs of analogical and numerical modems for use on the old phone network public with flows going up to 56 kbps while going down and 48kbps while going up, with an encoding PCM in the two directions. (with a modulation QAM). Support of technology Modem-one-Hold . It is about an extension of V.90 Mode 2.

X - Data networks and communication by open system

X.1 international Classes users for the maltreatment and categories of access for the data networks and Numerical Networks to Integrated Services (ISDN).
X.3 Numbered list for the attributes of configuration and the terminals of communication.
X.21 Interfaces between DCE and DTE for operations synchornes on the public data networks.
X.25 Interfaces between DCE and DTE for operations of the terminals in packages mode and network connection of public data by dedicated circuits.
X.29 Definition of level 4 (Session Layer in OSI model) for the communication X.25. Ask connection and parameters X.3 for the negotiation used in the protocol X.29.
X.75 Interfaces between the DCE in a network. Primarily for the transport of the messages X.25.
X.110 Principles and international plans of routing for public data networks.
international X.121 Plane of classification for the public data networks. Can be seen like the specification for the addresses of X.25.
X.200 Technology of information - ISO - Model of basic Reference: The Basic Model
X.208 Specifications of the Notations of Abstract syntax 1 (ASN.1) (exceeded by X.680)
X.209 Specification of the rules of basic encoding for the Notations of Abstract syntax 1 (exceeded by X.690)
X.400 Management of the services of messages: Overflight of the systems and services of management of the messages.
X.500 Technology of information - ISO - Field: Overflight of the concepts, models and services. Common texts with ISO/CEI
X.509 Technology of information - ISO - Field: Public keys and framework of attribution of Certificate S.
X.520 Technology of information - ISO - Field: Types of selected attributes
X.521 Technology of information - ISO - Field: Classes of objects selected
X.680 (series) - Specification of syntaxes ASN.1
X.690 (series) - Rules of encoding for ASN.1
X.700 Frameword de Management for ISO in application CCITT.
X.701 Technology of information - ISO - Overflight of the systems of management.
X.800 Architecture of safety for ISO in application CCITT.

Y - Total infrastructure of information and aspects of protocols Internet

Z - Languages and system software aspects for the communication systems

Z.200 the computer programming language CHILL. It should be noted that language CHILL (CCITT HIgh Level Language, language of CCITT high level) is used in France by France Telecom for the programming of the automatic exchanges of public phone network STN (Phone network commutated) and ISDN.

Sources

Internal bonds

universal Time coordinated
International office of the weights and measures
: Category: Recommandation_de_l' UIT-T
Right of telecommunications

External bonds

Official site of the UIT

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