access and core networks. They sell network capacity and quality of service to service providers and mobile virtual network operators (MVNOs). This relationship is explained in Section 4.4.1. Network providers have often global ambitions in order to leverage on economy of scale. Service providers own user subscriptions. They package services and sell them to their users. To be able to offer, handle and charge for compelling services they normally own and operate some kind of service networks. They purchase capacity and quality of service from network providers if the network provider does not provide this role as well within the company. The expression home environment (HE) is related to actors with user subscriptions. HE is responsible for overall provision of services to users. HE-VASP stands for home environment value-added service provider. A value-added service provider provides ser- vices other than basic telecommunications service for which additional charges may be incurred. A VASP has an agreement with the home environment to provide services. VAS services are related to the service network and its enablers. See also Section 5.5. Three Main Sub-chains One sub-chain of actors handles the transport of bits. It can be called the 'bridging distance (BD) chain' or 'bit pipe provision chain' or 'connectivity value chain'. Other roles can be described as part of the 'adding value (AV) chain/web' or appli- cation/content value chain/web'. Content provision is necessary for TV, videos, games, shopping, advertising, education, banking, music and information. Telecom Business Sub-chains Source Enablers Application/Content/Goods value chain Content aggregators Devices value chain Connectivity value chain Figure 4.17 The chain of roles can be divided into three sub-chains A third chain embraces terminating devices and other devices that we can refer to as forming a 'device value chain'. See Figure 4.17. The BD actors are in principle service providers to the AV roles. The BD role might seem straight forward, but it i