The papers which appear in this book were presented by their authors at a Symposium hosted by the Centre for Communication System Research, University of Surrey, Guildford, United Kingdom, on 28-29 March 2007. The Symposium was organized under the aegis of COST Action 285: Modeling and Simulation Tools for Research in Emerging Multi-Service Telecommunications The Symposium focused specifically on recent advances in modeling and simulation methods, techniques, and tools for communications networks and services. COST the acronym for European COoperation in the field of Scientific and Technical research is the oldest and most broadly focused European inter-governmental vehicle for cooperative research. COST was established by the Ministerial Conference in November 1971, and is presently used by the scientific communities of 35 European nations to cooperate in common research projects supported by national funds. Hence, COST is a framework for scientific and technical cooperation, supporting the coordination of national research at the European level. COST s goal is to ensure that Europe holds a strong position in all fields of scientific and technical research by increasing cooperation and interaction among participating nations. COST Actions are cooperative networks that focus on specific basic and pre-competitive research issues, as well as on activities of public interest. Actions are apportioned among fourteen key scientific domains such as social sciences, natural sciences, information technologies, and engineering. COST Action 285 is one of 22 Actions in the Information and Commu- cation Technologies domain."