Use the Integrated Services Digital Network (ISDN) Service feature to provide a message-oriented signaling method by which information can be sent along with a call. The ISDN Service feature also gives you access to a variety of public and private network services and facilities.

The ISDN standard consists of Layers 1, 2, and 3 of the Open System Interconnect (OSI) model. Communication Manager can be connected to an ISDN by way of the standard frame formats: Basic Rate Interface (BRI) and the Primary Rate Interface (PRI).