IP Video Telephony Solution Components

Cisco introduced its IP video telephony solution in Cisco CallManager Release 4.0. With this solution, video is fully integrated into Cisco CallManager, and new endpoints are available from Cisco and its strategic partners. Video is now just as easy to deploy, manage, and use as a Cisco IP Phone.

The Cisco IP video telephony solution consists of products and solutions:

• Cisco CallManager Release 4.0 or later. Cisco CallManager provides call routing and a centralized dial plan for voice and video devices.
• Cisco IP/VC 3500 Series Multipoint Control Units (MCUs) for both H.323 and Skinny Client Control Protocol (SCCP) videoconference calls. The MCUs are responsible for mixing the various video and voice streams in a videoconference. In a videoconference, all devices send their streams to the MCU; the MCU mixes these streams into a single picture and sends the mixed stream back to the endpoints.
• Cisco IP/VC 3500 Series H.320 gateways interconnect the IP world with the ISDN world. To interconnect the H.323 with the H.320 (ISDN) world, a video gateway is required. Unlike a voice gateway, a video gateway is able to bond bearer channels (B channels). An H.263 video call needs at least 128 kbps, at lowest quality, in each direction; the VT Advantage default for a video call is an H.263 384-kbps video call. For a 384-kbps call, the video gateway needs to open six ISDN B channels at the same time. The IP/VC 3500 Series H.320 gateways support B-channel bonding. The IP/VC 3500 Series H.320 gateways require an H.323 gatekeeper to register.
• A Cisco IOS H.323 gatekeeper is required to register third-party H.323 devices and the 35XX MCU. The main tasks of an H.323 gatekeeper are endpoint registration, bandwidth management, and directory number (DN) resolution. Many video devices, such as H.323 MCUs or H.320 video gateways, require an H.323 gatekeeper for registration.
• Cisco Video Telephony (VT) Advantage is a video telephony solution comprising the Cisco VT Advantage software application and Cisco VT Camera, a video telephony Universal Serial Bus (USB) camera. With the Cisco VT Camera attached to a PC collocated with a Cisco IP Phone, users can place and receive video calls on the enterprise IP telephony network. Users make calls from Cisco IP Phones using familiar telephone interfaces, but calls are enhanced with video on a PC, without requiring any extra button-pushing or mouse-clicking.
• TANDBERG SCCP endpoints are developed by the videoconference equipment vendor TANDBERG under Cisco license.
• The existing range of H.323-compliant products from vendors such as Polycom, TANDBERG, Sony, VCON, and VTEL Products. (Most H.323 video devices require a gatekeeper to register.)
• The Cisco 7985 IP Phone is one of the newest IP Phones added to the Cisco fleet. The 7985 supports full videoconference capabilities out of the box.
• Cisco IP Communicator 2.0 and later allows you to integrate the VT Advantage solution with the on-screen IP Communicator softphone.

Cisco CallManager Release 4.0 and later adds support for video in both the SCCP and H.323 protocols. Cisco CallManager can now manage H.323 endpoints, MCUs, and gateways, providing the system administrator with PBX-style control over all call routing and bandwidth management for those devices.

The video telephony solution consists of end-user devices, infrastructure, and applications. The end-user devices include video phones, soft video phones for remote workers (such as Cisco IP Communicator 2.0), and desktop environments that incorporate existing telephones and desktop computers. Additionally, the existing H.323 endpoints that the customers already own will become part of the video telephony environment.

Cisco CallManager is the center of the IP telephony infrastructure and supports both voice and video telephony. Cisco CallManager provides a single dial plan for all endpoints; there is no need for an additional video dial plan. The same applications are still supported: voice mail, conferencing, and scheduling for audio and video resources are possible.

The video stream mixing is accomplished by the MCU. In a Cisco CallManager environment, the MCU can be SCCP or H.323 or SCCP- and H.323-controlled. The main difference is that the H.323-controlled MCU needs an H.323 gatekeeper to register.

To allow external H.320 parties to participate in a videoconference, a video gateway, such as the Cisco IP/VC 3521 BRI Videoconferencing Gateway or IP/VC 3526 PRI Videoconferencing Gateway, is required. The normal voice gateways used in the Cisco CallManager environment do not support ISDN B-channel bonding and cannot route video calls from and to the public switched telephone network (PSTN).