This volume contains the proceedings of TestCom 2003, the IFIP TC6/WG 6.1 International Conference on Testing of Communicating Systems, held in Sophia Antipolis, France, during May 26-28, 2003. TestCom denotes a series of int- national working conferences on testing communicating systems in the data and telecommunication domain. The conference provides a forum for researchers, vendors and users to review, discuss and learn about new approaches, concepts andexperiencesinthe?eldoftestingofcommunicatingsystems.Thisconference in particular focuses on new ways of testing for new-generation networks. TestCom2003isthe?fteenthinaseriesofannualmeetingssponsoredbyIFIP TC6/WG6.1.The14previousmeetingswereheldinVancouver,Canada(1988), Berlin, Germany (1989), McLean, USA (1990), Leidschendam, The Netherlands (1991), Montreal, Canada (1992), Pau, France (1993), Tokyo, Japan (1994), Evry, France (1995), Darmstadt, Germany (1996), Cheju Island, Korea (1997), Tomsk, Russia (1998), Budapest, Hungary (1999), Ottawa, Canada (2000), and Berlin, Germany (2002).The scope of the papers presented at TestCom 2003 covers interoperability testing, TTCN-3, automata-based testing, testing of next-generation networks, IPandUMTS,testsystemsandtools,testspeci?cationdesignandmethodology, and industrial experience in testing communication systems. TheTestCom2003programconsistedof6technicalsessions,3positionsta- ment sessions, and a special session on interoperability testing. Three invited speeches gave an overview on actual trends in the testing and telecommuni- tion area and formulated requirements to the testing process. The proceedings contain the 19 regular papers accepted and presented at the conference. They were selected from 53 submitted papers in a careful selection procedure based on the assessment of three referees for each paper. The p- ceedings also include the text of the invited talk by Elaine Weyuker, Philippe Cousin, and Ana Cavalli.
