Virtual walled-garden model for IMS services provisioning

The IP multimedia Subsystem (IMS) is seen as a key clement for achieving network convergence defining a new horizontal integrated service offering, based on a common signaling protocol (SIP) for all multimedia services such as Voice over IP, Video call, or instant messaging. However the present deployment of IMS is specified according to a specific model, the so called Walled-garden. In this model the applications are only provided to the users within the same operator so that the users will not have to look for applications outside the IMS garden. It is a very restrictive access mode for the users because they remain dependent on services offered by the provider and can consequently not choose freely applications they went to subscribe for. The goal of this paper is to propose a new Service provisioning model: Virtual Walled-Garden. This new model allows the user accessing all the applications, even the external ones transparently, simulating a walled-garden environment. We also introduce the notion of security level to classify the SPs in a Multi-level model.