Revision with unchanged content. The realization of ubiquitous access to Internet services in the next generation of mobile networks (NGN) needs to address the increasingly important challenges of networks cross-bridging, mobility and Quality of Service (QoS) for different kinds of multimedia services. Current mechanisms for providing QoS cover predominantly single facets of the global QoS management. However, QoS is a system aspect that crosses all components and layers of a distributed multimedia system. Consequently, the control mechanisms for service management turn to be increasingly complex with the growing system heterogeneity. Significant parts of this work are devoted to the optimisation of the control signalling for distributed multimedia services. The major topic of this work is the specification and the implementation of the End-to-End Negotiation Protocol (E2ENP). The protocol represents a novel approach to manage multimedia services in mobile and heterogeneous networks, different from the currently existing static service-coordination methods. This book is the publication of the doctor thesis of T. Guenkova-Luy and it addresses the topics of optimization of the multimedia-management systems in NGN.