IP Video Telephony
Revised: June 08, 2010; OL-19142-02
All Cisco Unified Communications video endpoints and video applications support IPv4 only for video streams. In the majority of cases, calls between video phones use IPv4 for both voice and video media streams. There is one exception, however, which involves calls using Cisco Unified Video Advantage.
Cisco Unified Video Advantage is a Windows-based application and USB camera that you can install on a personal computer running Microsoft Windows. When the PC is physically connected to the PC port of a Cisco Unified IP Phone running the Skinny Client Control Protocol (SCCP), the Cisco Unified Video Advantage application "associates" with the phone, thus enabling users to operate their phones as they always have but now with the added benefit of video. Cisco Unified Video Advantage can also be associated to Cisco IP Communicator running SCCP on the same PC, in which case both voice and video streams will use IPv4).
Unlike all other Cisco video endpoints, when Cisco Unified Video Advantage is used in conjunction with an IP phone, the voice and video media streams do not originate from the same device. In this case, the voice streams originate and terminate on the IP phones, and the video streams originate and terminate on the PCs hosting the Cisco Unified Video Advantage camera.
Video streams from all Cisco video devices support IPv4 only. In the case of Cisco Unified Video Advantage, IPv4 is used for its video stream, but the IP addressing version used to transport the voice media between the IP phones may be IPv4 or IPv6. The IP addressing version used for the voice streams depends upon the capabilities of the phones, the addressing mode settings of the phones, and the cluster-wide IP Addressing Mode Preference for Media (in the case of a call between two dual-stack phones). Figure 12-1 shows an example of addressing mode selection with Cisco Unified Video Advantage.
Figure 12-1 Addressing Modes for Voice and Video Media Streams with Cisco Unified Video Advantage
Video calls can be made across ANAT-enabled dual-stack SIP trunks that are configured to use Delayed Offer. In the majority of cases, both the voice and video streams for these calls will use IPv4. The exception mentioned previously for Cisco Unified Video Advantage also applies to calls over SIP trunks, in which case SIP will negotiate IPv4 for video and can negotiate either IPv4 or IPv6 for voice.