With the introduction of smartphones and tablets and the dramatical increase of the data traffic on the cellular network, operators are seeking for new solutions to provide the users with continuous connectivity while preserving a good quality of service. Since most of current user terminals are equipped with multiple interfaces, one solution is to take advantage of the different access networks. However, with the current network architectures and user application, it is not possible to use both accesses at the same time or even to switch from one to another without loosing current sessions. In this paper, we present and analyse the main mechanisms of the literature that allow a user to use multiple access networks at the same time or to move between the different networks. We show how a converged network can permit the deployment of new solutions and present some of them accompanied by use cases.