Thebeginningofthe21stcenturyiswitnessingadrivetotheconvergenceof?xed and mobile telecommunication networks and the increasing adoption of IP te- nologies for implementing seamless multimedia applications in next-generation networks. The IEEE International Workshop Series on IP Operations & M- agement (IPOM) is documenting this evolution by providing snapshots of the state of the art in the ?eld of operations and management in IP-based networks. The 5th IEEE International Workshop on IP Operations & Management (IPOM2005),devotedtothe"O&MChallengesinNextGenerationServicesand Networks", was held in Barcelona, Spain, October 26-28, 2005. Here IPOM was one of the ?ve collocated events under the banner "First International Week on ManagementonNetworksandServices(www.manweek2005.org)",togetherwith the 16th IFIP/IEEE International Workshop on Distributed Systems: Ope- tionsandManagement(DSOM2005),the8thInternationalConferenceonM- agement of Multimedia Networks and Services (MMNS 2005), the 2005 Sym- siumonSelf-stabilizingSystems(SSS2005)andthe1stIEEE/IFIPInternational Workshop on Autonomic Grid Networking and Management (AGNM 2005). Thisbookcontainstheo?cialproceedingsofIPOM2005.Itfeatures21hi- quality papers grouped into seven technical sessions looking at O&M for VoIP, IMS and managed IP services, management of open interfaces, QoS and pricing in NGNs, autonomic communications, policy-based management, routing and topologies, routing and tools, as well as experiences from testbeds and trials. Additional papers presented in two short sessions are published separately. Wewouldliketothanktheauthorsforalltheire?orts,aswellasthemembers of the Technical ProgramCommittee, and the reviewers. Without their support the high-quality program of this event would not have been possible. We are also indebted to many individuals and organizations that made the conference possible (IEEE, IARIA, Fraunhofer Institute FOKUS, JEMS's drivers, and the Universitat Polit' ecnica de Catalunya).