Also known as a conference bridge or a teleconferencing bridge, a teleconference bridge is the collective name for the collection of equipment that makes it possible to terminate a number of audio and video connections at a common destination. The bridge itself normally functions by receiving inbound signals from the local telephone switch and confirming those signals with an outbound return signal. Over the years, this type of teleconference equipment has become increasingly efficient and makes it possible to conduct conference calls for as few as two locations all the way up to conferences that contain tens of thousands of connections.
A basic teleconference bridge includes a server that processes the inbound signals received over local phone switches. The bridge server also processes outbound signals made using the local switch, much in the same fashion that any type of telephone call is made. What makes this possible is the capacity of the server to send and receive multiple audio and video signals using trunks, or lines that are numbered and identified within the server itself. Once the connection is established, the call can be routed into a particular conference, by means of computers connected to the server. Once the callers are routed to the correct conference, they are free to talk to each other.
The earliest models of the teleconference bridge were huge devices that were limited to no more than a few lines that could be utilized for any given conference call. Until the early 1990’s, the signals carried on the bridges were strictly analog. As digital technology advanced, it was possible to increase the capacity of the bridges, with the earlier 32 and 64 port bridges replaced by models that were capable of supporting up to 128 lines. Over time, video capacity was added, and the line capacity also increased. Today, it is possible to hold a conference call that contains thousands of connections, if desired.
Enhancements to teleconference bridges over time has also allowed a wider format for conference calls than was possible as recently as two decades ago. At one point, conference call operators had to dial out to each attendee and manually bring the connection into a specific conference session. During the latter part of the 1990’s, the ability for attendees to dial in using a toll or toll-free number became common. When paired with a numeric pass code, the attendees could enter the correct conference without the aid of an operator.
By the middle of the 1990’s, video conferencing was becoming increasingly common. With this application, the teleconference bridge would not only establish audio connections, but also establish visual connections to conference rooms that were pre-certified to receive the video signal. The earliest configurations of these bridges were somewhat sensitive. This resulted in situations where any problems with the video connections would sometimes also cause the audio portion of the call to fail, making it necessary to reconnect the entire meeting. Further enhancements to the teleconference bridge designs of the day made it possible to continue with the audio portion even if some issue with the video feed developed.
The advent of the Internet has made a huge difference in the way that most teleconference bridge designs function today. A third alternative to conferencing, usually referred to as a web conference, makes use of Internet connectivity to create a meeting with both voice and graphics, such as text documents, spreadsheets, and even slide presentations. While much of the signaling is established via the Internet, the traditional teleconference bridge still serves as the means of receiving signals that are converted at the local phone switch and routed to the bridge for processing.