Service Features (SF) in intelligent networks (IN) are the reusable parts of a service, the Service Independent Building Blocks
(SIB). New partial services or a complete new service can then be formed from these SIB blocks. For the development of new services, the independent Building Blocks are linked together and the Service Feature is realized as a user interface. Service Features are provided at the service-oriented layer of the IN layer model, the Service Plane
(SP). There are several examples of such Service Features. These include freephone, authentication, time- or location-based switching techniques, subscriber location, or custom announcement services. In the above services, there are basic functions and features that are used in other services.