Will the `circuits to packets' revolution pave the way to the `protocols to APIs' revolution?

This paper addresses the question of the Service Layer structure in Next Generation Networks (NGN). Currently, most of the effort focuses on the introduction of an IP-based transport infrastructure, while little attention has been paid to new services. Indeed, the introduction of NGN is an opportunity that must be exploited by the Telecom Operators in order to enable a renewal in the service offering. This paper focuses on services and service features that could be introduced on NGN and the issues related to the introduction of a service control layer to support them.