Series and Recommendations
It issues recommendations that have names like X.500, where X is the series and 500 is a serial number.
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, full duplex 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, with fallback to 12000 bits/s.
- V.34 is the ITU-T standard for full-duplex data communications up to 28,000 bit/s with fallback to lower speeds depending on the remote modem ant the conditions of the phone line.
- V.42bis Data compression procedures for data circuit terminating equipment (DCE) using error correction procedures to try to ensure the transfer of error-free data, even over the noisiest telephone lines. Ratified by CCITT in January 1990.
- 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
- V.92
- 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
