B-ISDN
ATM provides broadband ISDN (B-ISDN) with both bearer services and circuit switching services.
ATM functions can be described in the following reference model. This layering model must not be mixed up with the OSI reference model; also, it cannot be seen as a part of it. The OSI reference model describes data communication functions based on packet switching systems (absolute station and network addresses coded in each frame); the B-ISDN reference model describes voice, video, and data communication functions based on circuit switching systems (station and network addresses replaced by virtual channel / virtual path IDs).