In this paper, CCF(Call Control Function), functional entity for basic call processing in SSP(Service Switching Point), is designed and implemented. This functional entity can provide the IN(Intelligent Network) services which are included in CCITT CS-1(Capability Set-1), near-term process for IN Architecture. UIO(Unique Input Output) method, one of the thest sequence generation methods for the finite state machine, is used for the implementation test of this functional entity.