This Recommendation defines the Intelligent Network Application Protocol, (INAI') required for support of Intelligent Network Capability Set 1. It supports interactions between the following four functional entities (FE'S), as defined in the IN functional model: Service Switching Function (SSF); Service Control Function (SCF); Specialized Resource Function (SRF); Service Data Function (SDF). The scope of this Recommendation is the further development of the INAP for both the Integrated Services Digital Network (ISDN) and Public Switched Telecommunications Network (PSTN).