This report examines the findings of a study by Bell Atlantic, IBM, and Siemens which investigated the role of the Intelligent Network in telecommunications. It considers current trends and future developments, on a national and international level. This report defines and describes the concept of the Intelligent Network and considers the operating requirements (including the hardware and software) and the types of service a network user can expect. Concepts, definitions, and terminology reflect the status of the Intelligent Network in 1988. Actual implementation may differ due to the constantly changing environment, new requirements, and experiences with existing solutions. The report is divided into six parts: Part 1 introduces the concept of the Intelligent Network, and describes elements common to alLIN services. It considers the application program and network management requirements, and provides examples of the hardware and software proposed for implementing the network. Parts 2 through 6 include detailed descriptions of specific IN services. In each part there is a functional service description and an application description. The reader is expected to have a general knowledge and understanding of existing telecommunication networks.