Quo vadis, IMS? Position and perspectives for the IP Multimedia Subsystem in a mobile networking context

According to the unanimous estimation of network operators, service providers, equipment manufacturers and international standardization bodies, the 3GPP IP Multimedia Subsystem (IMS) at present is the most promising approach for the basic architecture of a Next Generation Network (NGN), which is supposed to bridge the current gap between circuit-switching and packet-switching networks and to consolidate both sides into a single network for all services. Therefore, the imminent commercial introduction of IMS will be of tremendous impact both for the migration of the core network and the integration of future mobile services and applications. In this context, the present article investigates position and perspectives of IMS in a mobile networking context as developed within the ftw.-project CAMPARI. The first part of the paper starts with a survey of this project and describes our realization of an open source-based experimental testbed as minimal version of a widely standard compliant IMS core network. Based on this, in the second part we then discuss some basic open issues related to IMS charging, identity management, migration, security and regulatory aspects like IMS emergency calls and legal interception.