A set of specifications from the ITUT for an integrated services digital network (ISDN) requiring transmission channels capable of supporting rates greater than the primary rate, which is defined in the North American primary rate interface (PRI) standard as 1.544 Mbps and in the European primary rate access (PRA) standard as 2.048 Mbps.There are three underlying sets of technologies and standards critical to B-ISDN:
(Broadband-ISDN) A framework for advanced telecommunications from the ITU. Introduced in 1988 as an extension to ISDN, it was designed to provide a blueprint to integrate data, voice and video in the 21st century. B-ISDN specifies the use of ATM for switching and SONET for high-speed links. See ATM and SONET.