Intelligent Network Capability Set-4 (IN CS-4) is the fourth standardized stage of the Intelligent Network (IN) as anarchitectural concept for the creation and provision of network services, including telecommunication services, servicemanagement services and service creation services. This Recommendation gives the distributed functional plane for INCS-4. It describes the main characteristics and overall capabilities of the IN CS-4 functional architecture, network aspects and functional relationships that form the basis for IN CS-4. Chapter 4 describes the generic functional model at the control plane and illustrates how IN and IP may be seen to inter-work. Chapter 5 describes the relationships and interfaces that are enhanced, when related to the previous IN Capability Sets. Chapter 6 illustrates a number of important scenarios for inter-working and interoperability between IN and other networks not specified before in earlier IN Capability Sets. Annex B describes the relation between the generic control plane functional architecture and other allied functions that may be present in the underlying network.