This book comprises a strictly refereed selection of papers presented at three international workshops on advanced communication services (ACoS'98), visualization issues for formal methods (VISUAL'98), and advanced intelligent networks (AIN'97). The 20 revised full papers included in the book together with three invited presentations are centered around the user-friendly design of software systems and services, in particular telecommunication and Internet services, and visualization support for the design and administration of such systems. Among the topics addressed are telecommunication services, multimedia networking, user interfaces, intelligent networking protocols, formal specification and verification, visual formalisms, mobile computing, intelligent agents, and Java.