/mcpFor details on setting up presentation sources, see the video endpoint user guide. Note When two H.239-enabled endpoints attempt to establish a video call, they declare their video capabilities for the main video channel for meeting participants and their extended video capabilities (H.239 capabilities) for the second video channel. The following contents comprise H.239 capability signals: 1. The endpoints send signals to indicate that the devices support H.239. They also send associated commands and indication signals for managing the second video channel. This enables both the endpoints to be aware that the call is capable of opening multiple video channels. 2. The endpoints sends out one or more extended video codec capabilities to express video codec capabilities for second channels. The endpoint must specify the role of the second video channel. The defined role labels can be • Live-video-This channel gets processed normally and is suitable for live video of people • Presentation-This channel relays a token-managed presentation that is distributed to the devices After the capabilities have been exchanged, both endpoints immediately open two-way audio channels and the main video channels as in the traditional video calls. Opening Second Video Channels Depending on the third-party endpoint implementation, the second video channel is handled differently among vendors. Natural Presenter Package by Tandberg Video endpoints initiates the second video channel on demand. A video endpoint device does not open the second video channel immediately after the main video channel is established. The second channel gets opened when one of the callers (the presenter) specifies the source of the presentation and invokes a command to start the presentation. When a video endpoint user decides to start sharing the presentation, video endpoint requests the other call party to open an extended video channel for receiving the presentation image; therefore, a video endpoint-video endpoint call has only one-way second video channel. People + Content by Polycom Unlike video endpoint, a Polycom video endpoint initiates the second video endpoint immediately as a part of the default mechanism, after both parties have confirmed that additional video channels can be supported. Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 867 SIP Interoperability Opening Second Video Channels