We discuss the requirements, a model and protocol for the out-channel interaction for PCS in Intelligent Networks. As PCS can utilize the DSSI function (i.e. location update, authentication), it is reasonable to consider a model and protocol of the interaction for PCS as well as DSSI. To obtain the model/protocol, two types of interactions, call-related and call-unrelated, are considered. It is necessary to enhance the Basic Call State Model (BCSM) for the former, and to introduce a state model similar to BCSM for the latter, which represents association management and component exchange between a user and the network. The authentication function allocation for the dominant traffic, location update, is discussed based on the model and protocol, and this can co-exist with the proposed generic model and protocol.