/mcp• Some vendors implement call setup in such a way that they cannot increase the bandwidth of a call when the call gets transferred or redirected. In such cases, if the initial call is audio, users may not receive video when they are transferred to a video endpoint. • No video media termination point (MTP) nor video transcoder currently exists. If an audio transcoder or MTP is inserted into a call, that call will be audio only. This is true when the IPVC audio transcoding capabilities is not being used. When the IPVC transcoders are used, you can transcode the audio and send/receive video. • For H.323 video calls, users must specify video call bandwidth. H.239-Extended Video Channels in H.323 Call The extended video channels feature works via H.239 protocol and enables multiple video channel support. Cisco Unified Communications Manager supports negotiating an extended video channel using the H.239 protocol in direct point-to-point H.323 calls. This also includes calls across the H.323 intercluster trunk. Cisco Unified Communications Manager supports all H.239 associated support signals and commands that are specified in the H.239 recommendation. The following sections describes characteristics which apply to the extended video channels feature. Support for Third-Party H.323 Devices The extended video channel feature supports H.239 interoperability among third-party video endpoints and Cisco Unified Voice Conferencing. Cisco Unified Communications Manager allows an extended video channel to be used for presentation and live meeting transmission. This feature focuses on multiple video channel support via H.245 signaling. The following presentation applications provide basis for this multichannel support: • Natural Presenter package by the third-party vendor video endpoint • People + Content by the third-party vendor Polycom Both Natural Presenter package and People + Content use the H.239 protocol to negotiate capabilities and define the roles of the additional video channels. Natural Presenter package by video endpoint and People + Content by Polycom only support H.239 for the presentation mode. Be aware that the presentation applications that are offered by video endpoint and Polycom are optional features. You must have one of these options and H.239 enabled in both caller and callee endpoints to negotiate second video channels or the call will be limited to a single video channel. Note H.323 Devices Invoke Presentation Feature Cisco and Polycom video endpoints allow the user to share presentation materials from various components (for example, VCR, Projector, PC, and so on). The components can physically connect with the endpoints, and the PC can also run presentation applications that are provided by the vendor to transmit the presentation image. The source of presentation and the component connection with the video endpoint are irrelevant to the mechanism of establishing video channels by using H.239. Feature Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs 866 SIP Interoperability H.239-Extended Video Channels in H.323 Call