ITU-T - Wikipedia

ITU-T is the telecom standardization organization, previously known as CCITT, of the International Telecommunication Union (ITU). CCITT stood for Comité Consultatif International Telegraphique et Telephonique: the Consultative Committee for International Telegraphy and Telephony.

It issues recommendations that have names like X.500, where X is the series and 500 is a serial number.

See also:

ITU-R

See ITU-T's own website, http://www.itu.int/ITU-T/

Significant ITU-T series and recommendations are:

A - Organization of the work of ITU-T
B - Means of expression: definitions, symbols, classification,
C - General telecommunication statistics
D - General tariff principles
E - Overall network operation, telephone service, service operation and human factors
- E.123[?] Notation for national and international telephone numbers
- E.163 Numbering plan for the international telephone service
- E.164 The international public telecommunication numbering plan
  - Supplement 2 - Number Portability
F - Non-telephone telecommunication services
G - Transmission systems and media, digital systems and networks
- G.711 Audio compression (mu-law)
- G.723.1 Audio compression
- G.729[?] Audio compression
H - Audiovisual and multimedia systems
- H.225.0[?] Also known as RTP
- H.261[?] Video compression standard, circa 1991
- H.263 Video compression standard, circa 1995
- H.263v2 (a.k.a. H.263+) Video compression standard, circa 1998
- H.264 Video compression standard (also known as MPEG-4 part 10)
- H.323 Packet-based multimedia communications systems
  - Annex D - Real-time facsimile over H.323 systems
  - Annex G - Text conversation and Text SET
  - Annex J - Security for H.323 Annex F
  - Annex K - HTTP based service control transport channel in H.323
  - Annex M.1 - Tunnelling of signalling protocol (Qsig) in H.323
  - Annex M.2 - Tunneling of signalling protocol (Isup) in H.323
- H.332[?] H.323 extended for loosely coupled conferences
I - Integrated services digital network (ISDN)
J - Transmission of television, sound programme and other multimedia signals
K - Protection against interference
L - Construction, installation and protection of cables and other elements of outside plant
M - TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits
N - Maintenance: international sound programme and television transmission circuits
O - Specifications of measuring equipment
P - Telephone transmission quality, telephone installations, local line networks
Q - Switching and signalling
R - Telegraph transmission
S - Telegraph services terminal equipment
T - Terminals for telematic services
U - Telegraph switching
V - Data communication over the telephone network
- V.1[?] Equivalence between binary notation symbols and the significant conditions of a two-condition code
- V.24[?] List of definitions for interchange circuits between data terminal equipment (DTE) and data circuit-terminating equipment (DCE) - equivalent to EIA[?] RS 232[?]
- V.32[?] A family of 2-wire, duplex modems operating at data signalling rates of up to 9600 bit/s for use on the general switched telephone network and on leased telephone-type circuits
- V.32bis[?] A duplex modem operating at data signalling rates of up to 14 400 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits
- V.42bis[?] Data compression procedures for data circuit-terminating equipment (DCE) using error correction procedures
- V.90[?] A digital modem and analogue modem pair for use on the Public Switched Telephone Network (PSTN) at data signalling rates of up to 56 000 bit/s downstream and up to 33 600 bit/s upstream
X - Data networks and open system communication
- X.1[?] International user classes of service in, and categories of access to, public data networks and Integrated Services Digital Networks (ISDNs)
- X.21[?] Interface between Data Terminal Equipment and Data Circuit-terminating Equipment for synchronous operation on public data networks
- X.25 Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit
- X.110[?] International routing principles and routing plan for public data networks
- X.121[?] International numbering plan for public data networks
- X.200[?] Information technology - Open Systems Interconnection - Basic Reference Model: The basic model
- X.208 Specification of Abstract Syntax Notation One (ASN.1)
- X.209[?] Specification of Basic Encoding Rules for Abstract Syntax Notation One (ASN.1)
- X.400[?] Message handling services: Message handling system and service overview
- X.500 Information technology - Open Systems Interconnection - The Directory: Overview of concepts, models and services Common text with ISO/IEC
- X.509[?] Information technology - Open Systems Interconnection - The Directory: Public-key and attribute certificate frameworks
Y - Global information infrastructure and Internet protocol aspects
Z - Languages and general software aspects for telecommunication systems