Mixed Reality: A Survey

A multi-point-to-point conferencing system comprising a plurality of terminals connected by a network including data and control channels is disclosed. In a particular embodiment, the network is an Integrated Services Digital Network (ISDN) having data (B) channels and a control (D) channel. The conference is established in a manner that does not waste connection setup attempts or data channel connect time by attempting to establish a conference when a participating terminal does not have the necessary data channels available. The terminal initiating the conference communicates with at least one participating terminal to determine the use status, or availability, of the required number of data channels. If a participating terminal decides to join the conference, either automatically or through user confirmation, the participating terminal (1) reserves the required data channels for a limited time such that connection requests are only accepted from conference terminals and (2) communicates its decision to the initiating terminal. Now knowing that data channel connections can be successfully established between those terminals ready to participate, the initiating terminal initiates a conference using normal multi-point-to-point connection procedures.