CCITT

Abbreviation of Comit Consultatif International T l phonique et T l graphique, an organization that sets international communications standards. CCITT, now known as ITU(the parent organization) has defined many important standards for data communications, including the following:

  • Group 3: The universal protocol for sending fax documents across telephone lines. The Group 3 protocol specifies CCITT T.4 data compression and a maximum transmission rate of 9,600 baud. There are two levels of resolution: 203 by 98 and 203 by 196.
  • Group 4 : A protocol for sending fax documents over ISDN networks. The Group 400 protocol supports images of up to 400 dpiresolution.
  • V.21: The standard for full-duplex communication at 300 baud in Japan and Europe. In the United States, Bell 103is used in place of V.21.
  • V.22 : The standard for half-duplex communication at 1,200 bps in Japan and Europe. In the United States, the protocol defined by Bell 212Ais more common.
  • V.22bis : The worldwide standard for full-duplex modems sending and receiving dataacross telephone lines at 1,200 or 2,400 bps.
  • V.29: The standard for half-duplex modems sending and receiving data across telephone lines at 1,200, 2,400, 4,800, or 9,600 bps. This is the protocol used by fax modems.
  • V.32 :The standard for full-duplex modems sending and receiving data across phone lines at 4,800 or 9,600 bps. V.32 modems automatically adjust their transmission speeds based on the quality of the lines.
  • V.32bis:The V.32 protocol extended to speeds of 7,200, 12,000, and 14,400 bps.
  • V.34 :The standard for full-duplex modems sending and receiving data across phone lines at up to 28,800 bps. V.34 modems automatically adjust their transmission speeds based on the quality of the lines.
  • V.42 : An error-detection standard for high-speed modems. V.42 can be used with digital telephone networks. See MNPfor a competing standard.
  • V.42bis:A data compression protocol that can enable modems to achieve a data transfer rate of 34,000 bps.
  • V.90: The standard for full-duplex modems sending and receiving data across phone lines at up to 56,600 bps.
  • X.25: The most popular packet-switchingprotocol for WANs.
  • X.400: The universal protocol for e-mail. X.400 defines the envelope for e-mail messages so all messages conform to a standard format.
  • X.500: An extension to X.400 that defines addressing formats so all e-mail systems can be linked together.
  • Webopedia Staff
    Webopedia Staff
    Since 1995, more than 100 tech experts and researchers have kept Webopedia’s definitions, articles, and study guides up to date. For more information on current editorial staff, please visit our About page.

    Related Articles

    @ Sign

    Pronounced at sign or simply as at, this symbol is used in e-mail addressing to separate the user' name from the user's domain name,...

    Munging

    (MUHN-jing) Munging (address munging), is the act of altering an email address posted on a Web page to make it unreadable to bots and...

    How to Create an RSS Feed

    In the second installment of RSS how-to, we look at some of the nonrequired (optional) channel and item tags, discuss RSS specifications in-depth and...

    Dictionary Attack

    (n.) (1) A method used to break security systems, specifically password-based security systems, in which the attacker systematically tests all possible passwords beginning with...

    ScalaHosting

    ScalaHosting is a leading managed hosting provider that offers secure, scalable, and affordable...

    HRIS

    Human resources information system (HRIS) solutions help businesses manage multiple facets of their...

    Best Managed Service Providers...

    In today's business world, managed services are more critical than ever. They can...