ITU-T Recommendation for Using Multiple Video Channels

C.

H.239 is the ITU standard for a second video channel; this is supported by all the major vendors, and is the only content channel standard supported by Cisco acquired Codian products or Cisco TelePresence Serial Gateway Series products on H.323 video calls.Cisco acquired Codian products need to be configured to enable H.239

Any H.323 endpoint that also supports the H.239 protocol can source this channel, as can a VNC connection, though some endpoints need to be configured to use H.239 instead of their proprietary solution.

The ITU-T is a standardization sector of the International Telecommunication Union that defines global telecommunications standards. The ITU-T has defined several recommendations related to videoconferencing, including the use of multiple video channels.

The correct answer to this question is D. H.239. ITU-T Recommendation H.239 defines the procedures for using more than one video channel in videoconferencing systems. Specifically, H.239 describes the use of a second video channel for transmitting presentation data, such as slides or documents, during a videoconference.

H.239 is commonly used in conjunction with other videoconferencing standards, such as H.323 and SIP (Session Initiation Protocol). H.323 is a standard for multimedia communication over IP networks, and SIP is a protocol used for initiating, maintaining, and terminating real-time sessions that involve video, voice, messaging, and other communications applications.

H.324 (answer B) is a standard for transmitting audio and video over circuit-switched networks, such as the public switched telephone network (PSTN). H.230 (answer C) is a recommendation for the interface between audiovisual equipment and digital networks. H.264 (answer E) is a video compression standard that is widely used in videoconferencing and other applications. H.329 (answer F) is not a valid ITU-T recommendation.