Video dial tone sessions

Video dial tone (VDT) has brought together the diverse approaches of data communications, telephony, and cable television networks. VDT is one of many new terms referring to a group of fast evolving technologies in the area of broadband interactive multimedia. Associated with VDT are a number of other terms and concepts that are combined in new and often inconsistent ways. The article defines what is meant by VDT and associated terms. It is based upon the experiences at Digital Equipment Corporation in developing a Level 1 Gateway for a number of ongoing VDT trials. It applies the resulting simple conceptual framework to a description and analysis of the signaling aspects of VDT. These aspects deal with the creation, maintenance, and release of VDT sessions, which allow interactive multimedia services to be delivered to service users. Most of the concepts and relationships associated with VDT services are merely the convergence of the distinct technologies comprising this emerging area. This convergence is the primary cause of the striking complexity of VDT services. Complexity is likely to be the biggest obstacle to the timely deployment of VDT technology. However, each of the underlying technologies is relatively well understood, so the primary requirement is to bring them together in a coherent and systematic manner. The article attempts to facilitate that process