Distributed PBX gateways to enable the hosted enterprise services architecture in a NGN scenario

In this paper architectural network evolution based on specific PBX-gateways is presented, in order to make it possible to efficiently integrate the PBX extensions in an IMS-based service layer. User-centric service architecture will offer services to the actual user, and not to the specific line or device. The future of such user-centric services to be offered by telecom operators depends on the efficient and realistic deployment of fully FMC convergent architecture as evolution of the current infrastructure. Operator needs to face significant adaptation and integration challenges described by the standards that will make the difference in order to get to the market with the appropriate strategic position and technological solution. Accordingly, services for Enterprises will be the first step towards the convergent scenario. However, corporations have performed significant investments on CPEs, on infrastructure and service logic, and operators shall propose a seamless way to evolve to a convergent picture without jeopardizing the customer´s investment. The proposed architecture uses standard protocols to integrate CPE service logic into horizontal network service layer, taking advantage of the CPE investment that the corporations are not willing to replace. Specific implementation details, signaling flows and pros/cons analysis for such architectural decisions are provided.