| The simplest form of videoconferencing is a | | | | display monitor at all times, much like the television |
| point-to-point call, one person contacting another | | | | show Hollywood Squares. |
| person via the Internet. This basic level of | | | | Interesting as Continuous Presence is, it is not the |
| videoconferencing is similar to making a phone call | | | | default mode for multipoint videoconferencing. The |
| with a picture phone. Multipoint videoconferencing | | | | default mode is Voice-Activated Switching, or VAS. |
| occurs when three or more locations connect | | | | In VAS a multitude of sites are connected and the |
| simultaneously, much like a three-way phone | | | | person all views speaking. This should bring to mind |
| conversation only the logistics are much more | | | | the image of a newscaster or spokesperson on |
| complex. | | | | standard television. |
| To begin understanding the complexity of multipoint | | | | An important point in the VAS mode is that although |
| conferencing one must enter the domain of | | | | the transmission focus will be on the one who is |
| technology and begin with ISDN. ISDN means simply | | | | speaking, anyone and everyone connected to the |
| Standards for Integrated Services Digital Network, a | | | | videoconference can change the view. Remember |
| high quality, switched digital communications service | | | | the term is voice-activated. If someone coughs or |
| that gives your standard phone line the ability to | | | | sneezes, the camera recognizes them. In VAS |
| transmit voice and data simultaneously. | | | | multipoint videoconferencing it is very important to |
| You can use the same line for regular telephone | | | | mute your microphone until it is your turn to speak. |
| service, faxing, computer communication, or even live | | | | There are yet other modes of transmission for a |
| videoconferences. Each of these applications requires | | | | multipoint videoconference. These are Chair Control, |
| suitably equipped customer-provided equipment. ISDN | | | | Lecture Mode, and Broadcast with Autoscan. In Chair |
| transmissions are significantly faster than using a | | | | Control and Lecture Mode the presenter is seen |
| modem. Think of ISDN as a high-tech phone line. | | | | full-screen by all sites at all times, even if a speaker |
| The next essential ingredient in a multipoint | | | | at another site speaks. This mode is used primarily |
| conference is the bridge. This is a multipoint control | | | | with distance learning, when the situation requires |
| unit known as MCU, the component that manages | | | | that students always see the presenter rather than |
| the videoconferences when of three or more | | | | speakers at other remote sites. |
| participants are involved. | | | | Broadcast with Autoscan means only the director or |
| An MCU can support some or all of the following: | | | | presenter is able to view all the remote sites while |
| audio-only calls, video calls at various video | | | | the remote sites can see the video that is being |
| bandwidths, video calls, data sharing, continuous | | | | broadcast. This becomes even closer to a television |
| presence, cascaded calls, a conference call web page | | | | broadcast via the Internet. This mode is preferred |
| and component stacking. Component stacking can | | | | for videoconference presentations and seminars, |
| remain in the technicians domain but continuous | | | | when audience response is not anticipated or required |
| presence deserves attention by anyone who would | | | | and unlike a television broadcast, a multipoint |
| understand multipoint videoconferencing. | | | | videoconference in broadcast with Autoscan mode |
| Continuous presence, also know as the CP Mode is | | | | allows the director or presenter to view the audience |
| when all sites in the videoconference can be seen at | | | | and watch for response. |
| the same time on the far end monitors. Those | | | | In todays computer world most multipoint |
| involved in the videoconference will see themselves | | | | videoconferencing systems have built-in bridges which |
| (or any data that they present) on their right hand | | | | allow you to connect to multiple sites just as you |
| monitor while at the same time they can see | | | | would in a point-to-point call Even more |
| themselves and everyone else on the screen. | | | | advantageous is the rise in technology to include |
| Continuous presence is often used when presentation | | | | built-in gateways. A gateway is a network point |
| is required. As you can see, multipoint | | | | acting as an entrance to another network. This allows |
| videoconferencing with continuous presence | | | | communication across any set of interconnected |
| activated can be very effective for business or | | | | networks. |
| hospital transmission. Another way of looking at CP is | | | | This means the World-Wide-Web is now available for |
| seeing each site in a split screen format on the | | | | anyone interested in a multipoint videoconference. |