The technology for B-ISDN was going to be Asynchronous Transfer Mode (ATM), which was intended to carry both synchronous voice and asynchronous data services on the same transport.
The B-ISDN vision has been overtaken by the disruptive technology of the Internet. The ATM technology survives as a low-level layer in most DSL technologies.
wikipedia.org dumped 2003-03-17 with terodump