Cisco VT Advantage Overview

Cisco VT Advantage brings video telephony functionality to the Cisco IP Phone 7940, 7960, and 7970 (and later) models. Cisco VT Advantage software coupled with the Cisco VT Camera (a USB camera) allows a PC connected to a Cisco IP Phone to add video to telephone calls without requiring any extra button-pushing or mouse-clicking. When registered to Cisco CallManager, the Cisco VT Advantage-enabled Cisco IP Phone has the features and functionality of a full-featured IP video phone. Supplementary services, such as call forward, transfer, hold, and mute, are also available for video calls and are all initiated through the Cisco IP Phone. Cisco VT Advantage is intended for desktop-to-desktop IP video telephony environments, not as a general-purpose videoconferencing solution for use in conference rooms.

Cisco VT Advantage Components

To deploy Cisco VT Advantage, the minimum requirement is Cisco CallManager Release 4.0(1) with Service Release 2 or higher. Currently, you can enable video on Cisco IP Phone 7940G, 7960G, and the 7970G (and later) models. The Cisco VT Camera is connected to a PC (via USB) where Cisco VT Advantage software is installed. Cisco VT Advantage software works only with the Cisco VT Camera.

Note

Cisco VT Advantage and the Cisco IP Communicator (Softphone running on a PC) can run on the same PC; however, Cisco VT Advantage is not supported to interconnect with Cisco IP Communicator.

Cisco VT Advantage software provides the user with an easy-to-use graphical interface, with these options:

• Receive Only Mode Users can choose to view incoming video only and not transmit video.
• Video Check Users can check their video before calls are placed or received.
• Mute Video on Audio Mute When users mute the audio on the IP phone, video is automatically paused until the audio on the IP phone is restored.
• Video Signal Indicators The quality of the incoming and outgoing video is graphically displayed.
• Connectivity Indicator Graphics are used to indicate the state of the connections from the PC to its associated Cisco IP Phone and Cisco VT Camera.

Users can operate the Cisco IP Phone as they normally do. The Cisco VT Advantage software is controlled from the PC connected directly to the access port labeled "PC" on the back of the Cisco IP Phone. The PC and the Cisco IP Phone that is registered in Cisco CallManager as a video-enabled device build an association. The voice Real-Time Transport Protocol (RTP) streams flow between the two IP phones, as in a normal voice call. The video streams flow between the two PCs where the Cisco VT Advantage software is installed.

Cisco VT Advantage Supported Standards

Cisco VT Advantage, like any other application that runs on a PC, has an impact on system performance that should be taken into consideration. Cisco VT Advantage supports two types of video codecs: H.263 and the Cisco VT Camera wideband video codec. Of these two types, the Cisco VT Camera wideband video codec places the least demand on the PC. Therefore, if your network has plenty of available bandwidth, you can use the Cisco VT Camera wideband video codec and save on PC CPU and memory resources.

When you are using a codec that performs compression, more CPU power is needed. The H.263 codec is more demanding of PC system resources, but it requires less bandwidth. Therefore, if you want to use H.263 compressed video to conserve bandwidth on the network, you should ensure that your PCs have enough CPU and memory resources available. The Cisco VT Advantage H.263 codec supports a range of speeds up to 1.5 Mbps.

Regardless of the video standard used, the VT Advantage supports video formats with up to 30 frames per second (fps) at the following resolutions:

• VGA (640x480)
• CIF (352 x 288)
• SIF (320 x 240)
• QCIF (176 x 144)
• QSIF (160 x 120)

Table 29-1 lists the video codecs that Cisco VT Advantage supports.

Table 29-1. Video Codecs Supported by Cisco VT Advantage

Codec	Parameters
H.263	Bandwidth: 128 kbps to 1.5 Mbps Native Resolution: Common Intermediate Format (CIF) and Quarter CIF (QCIF) Frame rate: Up to 30 frames per second (fps)
Cisco VT Camera wideband video codec	Bandwidth: 7 Mbps Native Resolution: 320 x 240 Frame rate: Up to 30 fps

 

Protocols Used by Cisco VT Advantage

Cisco VT Advantage supports several industry-standard and Cisco networking protocols required for video communication. Table 29-2 displays an overview of the supported networking protocols.

Table 29-2. Overview of the Supported Networking Protocols

Networking Protocol	Description	Usage Notes
Cisco Audio Session Tunnel	Allows communication between the Cisco IP Phone and associated software, such as Cisco VT Advantage. Uses source and destination port 4224. Uses TCP. Cisco proprietary protocol.	Cisco Audio Session Tunnel is used between Cisco VT Advantage and the IP Phone - To build an association (after the PC discovers the IP phone using Cisco Discovery Protocol) - To send signaling information for video streams from the IP phone to Cisco VT Advantage (after the IP phone receives the signaling messages for both audio and video from Cisco CallManager) Cisco Audio Session Tunnel signaling messages include these: - Call video stream start and stop - Call hold and resume
Cisco Discovery Protocol	A device-discovery protocol that runs on all Cisco manufactured equipment. A Layer 2 protocol. Works only between directly connected neighbors. Using Cisco Discovery Protocol, a device can advertise its existence to other devices and receive information about other devices in the network. Cisco proprietary protocol.	Cisco VT Advantage uses Cisco Discovery Protocol to communicate its capabilities to the Cisco IP Phone, and the Cisco IP Phone uses Cisco Discovery Protocol to communicate information, such as its IP address, to Cisco VT Advantage.
RTP	A standard for using User Datagram Protocol (UDP) to transport real-time data, such as interactive voice and video, over data networks.	The RTP protocol is used to encapsulate and stream the audio (between Cisco IP Phones) and video (between Cisco VT Advantage endpoints).
Skinny Client Control Protocol (SCCP, or Skinny)	A Cisco protocol using low-bandwidth messages that allows the exchange of signaling messages between IP devices and the Cisco CallManager. Works on TCP port 2000. Cisco proprietary protocol.	Cisco VT Advantage does not use SCCP itself. It uses Cisco Audio Session Tunnel to send signaling messages to the Cisco IP Phone, which acts as a proxy and passes the signaling messages to Cisco CallManager using SCCP.