Performability Has its Price : 5th International Workshop on Internet Charging and QoS Technologies ICQT 2006 St. Malo France June 27 2006 Proceedings Keynote Cooperation and QoS in Fast Packet Networks: The View from the Edge Session 1: Economy Driven Modeling How Many Parallel TCP Sessions to Open: A Pricing Perspective Performance Modeling on the Interaction of ISPs Session 2: Auctions A Random Walk Model for Studying Allocation Patterns in Auction Based Resource Allocation A Simulation Based Approach to Bidding Strategies for Network Resources in Competitive Wireless Networks Session 3: Peer to Peer Charging in Peer to Peer Systems Based on a Token Accounting System A Market Managed Topology Formation Algorithm for Peer to Peer File Sharing Networks Session 4: Secure Billing Adapting a Captive Portal to Enable SMS Based Micropayment for Wireless Internet Access Secure Billing for Ubiquitous Service Delivery. This volume of the Lecture Notes in Computer Science series publishes the set of papers accepted for the ICQT 2006 workshop i.e. the 5th International Workshop on Internet Charging and QoS Technology (ICQT) which was collocated with ACM SIGMETRICS. These events took place in St. Malo France and were hosted by the IUT (Institut Universitaire Technologique) of St. Malo. QoS guaranteed services enable a huge variety of prosperous business models and the need for viable models and pricing schemes is urgent. The resulting combination of technical and economic perspectives drives many relevant research topics for application developers business architects network providers service providers and customers. Especially the identification of novel service charging solutions the investigation and evaluation of their technical feasibility and the consolidation of technical and economic mechanisms for enabling a fast guaranteed and efficient charging of services is of fundamental importance for the future evolution of the Internet and as such the central focus of the international ICQT workshop series. This year’s ICQT constituted the 5th vivid workshop on Internet economics and charging technology which initially took place in 2001 in Vienna Austria within the framework of the Annual Meeting of the German Society for Computer Science (GI) and the Austrian Computer Society and which was collocated in 2002 with the QofIS 2002 workshop in Zürich Switzerland in 2003 with the NGC 2003 workshop in Munich Germany and in 2004 again with QofIS 2004 in Barcelona Spain.