The B-ISDN (broadband integrated services digital network) is a virtual circuit-switched network that can use high-speed packet switching services. The B-ISDN will use a flexible multiplexing format called ATM (asynchronous transfer mode).
B-ISDN services are classified into interactive and distribution services. Interactive services contain the bidirectional flow of user information between two subscribers or between a subscriber and a service provider.
The interactive services are further divided into three sub-categories which are as follows−
Conversational service involves the real-time exchange of information such as sound, video, data or entire documents. Examples include video-telephony, video-conference, and high-speed data transfer. Video-telephony is like the normal video telephony service but also has video capture, transmission and display capabilities. Video-conference supports voice and video communication between two conference rooms or between several individuals.
Messaging service involves the non-real-time exchange of information between subscribers in a store-and-forward fashion.
Retrieval services provide subscribers with retrieval access to centrally-stored public information. Examples include broadband videotext (retrieval of video images/sequences with sound, text and graphics), video retrieval (subscriber create to video libraries of movies) and return of high-resolution pictures and records from multiple archives and data centers.
Distribution services contain the unidirectional flow of user information from a service provider to a subscriber.
Distribution services are divided into two sub-categories, which are as follows: