Video Conferencing F.A.Q.

Is there a difference between video conferencing and video teleconferencing? What is H.320 video conferencing? What is H.323 video conferencing? How do I know whether to buy an H.320 system or an H.323 system? What is a Codec? What is a Gatekeeper? What is an MCU? If I don't want to buy equipment, how can I use video conferencing? What factors affect quality? How many users or participants can I link together on a video conference? What types of telephone lines are required for a video conference? Can I use a regular telephone to participate in a video conference? Can I link callers on cellular phones into a multi-point video conference?   Is there a difference between video conferencing and video teleconferencing? a) When describing video conferencing systems, there is a common interchanging of words that mean the same thing. Video conferencing is the same as video teleconferencing. The phrases are both used to describe a meeting between parties in different locations wherein the meeting participants use communications equipment to both see and hear one another as they interact. b) There is similar usage for phrases associated with teleconferencing. Teleconferences are called both audio conferences and teleconferences. In each, three or more telephone callers are linked together in a telephone call with all parties hearing one another and some or all parties interactively speaking. What is H.320 video conferencing? a) H.320 is the name of the standard for video conferencing using what are called "switched services" like ISDN and Switched-56. The standard was established in 1990. There are a number of protocols related to the H.320 standard. This series of standards govern basic video communications including graphical communications and audio over commonly used time division multiplexed (TDM) circuits. b) This H.320 type of video conferencing has historically been the most popular and flexible. The standard governs communications over digital channels, similar to those your telephone uses deep within the telecommunications network. Frequently, in order to ensure a high degree of picture and sound quality, a technique called "inverse multiplexing" is used to aggregate channels for higher bandwidth. c) H.320 video communications systems are often used on networks where usage charges apply such as on networks that use ISDN services from local and long distance telephone companies. What is H.323 video conferencing? a) H.323 is the name of the standard for video conferencing using an IP network as the communications link. H.323 videoconference communication uses the Real-Time Protocol (RTP/RTCP) and it enables the use of video conferencing over IP networks, LANs and even over the Internet. Each system connects to others by dialing an IP Address rather than by using a telephone number (as in H.320 communications). b) Using H.323 image quality can be as good or better than H.320 video conferencing of comparable bandwidth. There are a number of issues with respect to H.323 video communications that do not affect H.320 communications. For example, the general nature of IP networks does not assure bandwidth availability that is essential for quality H.323 video communications. Several remedies are available to overcome this constraint, some of which include re-engineering entire corporate IP backbone networks to accommodate video conferencing. How do I know whether to buy an H.320 system or an H.323 system? Most systems today are H.323 capable. Some manufacturers charge extra to enable H.320 ports on their systems. Depending on your network design, it is usually best to have both H.323 and H.320 capability. This would allow for quick and easy H.323 setup in a campus environment with the ability to communicate securely outside of the campus with ISDN or other digital telephone lines using the H.320 protocol. What is a Codec? Codec stands for "Coder/Decoder". It is a piece of equipment or software that both encodes an audio/video signal from an analog source (like a camera or microphone) and decodes the digital signal for replay as an analog signal (to a monitor or speakers.) What is a Gatekeeper? A Gatekeeper is a software component that allows you to register each of your H.323 video conferencing users. This software allows you to set restrictions on bandwidth usage and function. You can define these settings on a case-by-case basis per site as each site registers (i.e. no restrictions on the company president), or on a global setting. This can be a good way to manage your H.323 video conferencing network and minimize the impact on your LAN. With a Gatekeeper, you can use aliases such as "Bill Smith" to connect parties rather than the more abstract IP address. A fictitious phone number such as "555-1111" can also be assigned as an IP "alias" and thus an IP network could be made to look and feel like a telephony network. What is an MCU? MCU stands for Multipoint Control Unit. It is a device that is used to connect more than two video conferencing endpoints at a time into one video conference session. Much like a large audio conference, an MCU joins multiple video conferencing participants into a single conference, allowing them to see and interact with each other. The participants will either see one site at a time as each participant speaks, or they will see some form of a grid showing all of the participants in a split screen. If I don't want to buy equipment, how can I use video conferencing? Call Techphonic at 866.874.6642, both our New York and Connecticut offices feature videoconferencing facilities available for rent.  What factors affect quality? The speed of the network connection is one of the biggest contributors to quality. If the network connection is slow or unstable (such as over the open internet) the video session can be unusable. Newer equipment (manufactured after 1999) can produce excellent motion pictures from even slow speed connections and therefore can significantly contribute to better quality images. Some seemingly minor factors can seriously affect quality. Microphone placement and function significantly affect video conference quality because the audio clarity of a meeting is critical to the perception of quality. Further, the amount of movement the meeting participants create, if great, can cause codecs (the video conferencing engine) to create blurred images as they process communications signals. Finally, the type-size of fonts used in computer presentations if too small can be illegible to both near and far-end meeting participants. Techphonic can offer assistance with all of these quality factors and more. Contact us for more information. How many users or participants can I link together on a video conference? Some video conferencing codecs are multi-site enabled. This means they can connect additional sites without the need for a multi-point conference unit (MCU/Bridge). While multi-site conferencing may be a feature on an endpoint, we recommend using an MCU when connecting more than 3 sites in a video conference. This will typically ensure higher quality video and bandwidth availability. What types of telephone lines are required for a video conference? a) For H.320 video conferencing, BRI ISDN lines either from your local Telco, or from your company's PBX are required. In some applications with special networks, leased T-1 lines, ATM networks, Primary Rate ISDN and/or Switched-56 circuits will also work well. b) For H.323 communications, a LAN (IP) connection, available bandwidth and some minimum amount of assured bandwidth is required. For business-grade communications no less than 128K of available bandwidth is essential. A VPN tunnel through the Internet may also be required for communication over a Wide Area Network. Can I use a regular telephone to participate in a video conference? Yes, however, if your organization uses a video conference bridge (MCU), it may not support mixing participants in this manner (i.e., video participants and telephone participants). You may be required to use an outside vendor, to link your audio and video conferences. TKO provides this service and we will be happy to answer further questions on "mixed" conferences. Can I link callers on cellular phones into a multi-point video conference? It is possible to connect someone on a cellular telephone into a conference, however, that connection is usually quite poor. Cellular callers often inject poor audio quality into a conference call or drop out of a conference due to signal loss.