The intelligent network (IN) is a worldwide concept which specifies the functions, interfaces, and service-independent building blocks for the implementation of value-added services in digital telecommunication networks. One example is UPT (universal personal telecommunication), a service for fixed network mobility, which is presently being standardized. This paper describes the evaluation and implementation of an advanced UPT service, which allows a reachability control for ISDN based on the signaling system no. 7 (SS.7) and the intelligent network, which depends on the user's present social role (work, meeting, travel, vacation, etc.). The paper applies models of the users' communication habits, the components, and network services, develops simulation and queuing models for the traffic analysis and evaluation; and determines the call setup time for the new services as well as the quantitative load on the signaling network. Different scenarios for the distribution of the functionality of the intelligent network are studied. Two prototypes of the advanced UPT service are described: an integrated implementation placed in the network, and a standalone implementation outside the network. These prototypes have been displayed at several conferences and fairs. Services of this type are of interest in view of new competitive value-added services.