Summary

Recommendation ITU-T H.239 defines the procedures for use of more than one video channel in ITU‑T H.320‑based systems, and for labelling individual channels with a "role", which indicates requirements for processing the channel and the role of the channel content in the call. Role labels are applicable to both ITU‑T H.320 and ITU‑T H.245 signalling-based systems. The defined procedures include control, indication and capability exchange mechanisms

This revised version introduces a number of typographical corrections and clarifications to the previous version, primarily the description of MCU procedures.