Telecommunication service description using state transition rules

For telecommunication software design, SDL (R. Tinker et al., 1986) functional specification description language is conventionally used for specification descriptions. The authors clarify difficulties of SDL description for supplementary services, which allow a conversation among an infinite number of customers, and where there is considerable service interaction behavior. They also propose a telecommunication service description method, STR (state transition rule) method. In the proposed method, the service among an arbitrary number of customers can be defined easily, and declarative description is allowed for service interaction behavior in the early stage of software design. The authors clarify a feature of the proposed descriptions, that monotonic increase of transition rules realizes easy service addition. Lastly, the analyzability of the proposed descriptions is discussed