 a model which combines aspects of private and public clouds. It is a merging model where some resources are offered via public clouds and com- bined with private cloud services. An example can be a business-critical application Enabling Service Delivery in Next-Generation Networks which is integrating public services with privately owned and hosted user data. Another example is where privately provided cloud services make use of publicly offered storage or computing resources for nonsensitive data storage and computing. In this way, the cost reduction promise of public clouds can be obtained while security and privacy measures for business data are fulfilled in the private cloud. 4.4 Cloud-Enabled Business Models: New Chances for the Telecommunication Market Besides the strong evolvement of cloud computing from the IT domain, the Telecom network and service environment provide a natural environment to serve consumer as well as corporate domains with trusted and secure cloud environments. This spans from an evolution of managed Telecom services usually offered in a shared mode toward Network as a Service adapting to the IaaS model, up to the challenges to address the so-called long-tail market [8] in order to utilize the service creation potential of reusable service components in the horizontal NGN service layer toward a new service market place offered via service creation PaaS solutions and the SaaS aggregation business opportunity for Telecom providers. In today's economically demanding times, flexibility in business, lowering costs, and increasing search for new revenues, Telecom providers start to invest more in the opportunities for cloud computing aiming to address all market segments. As they are well placed to deliver software and services on demand and on a pay-per- use basis to their enterprise and SMB customers, Telecom providers have a unique opportunity to exploit the various cloud types integrating their Telecom assets in network infrastructure, service portfolio for integration in new services, a