Next Generation Network (NGN) is an innovative revenue stream for the service providers from the increase of their service offerings. Therefore, it is important to understand how proposed solutions in NGN markets can enable flexible and easy service creation, delivery and management both to service providers as well as third party application developers. Consequently, this book provides guidelines for the NGN service platforms evaluation, in terms of functionality, programmability, flexibility, openness, and inter-operability. In other words, the objective is to revise some of the major benefits promised by NGN, namely productivity, creativity and new revenues from new business opportunities, and to overhaul how well current product offerings can support these capabilities with available service development tools.