IMS presents an innovation in the world of telecommunications by providing a concrete Control Platform; the platform enables the delivery of multimedia services with high QoS range and with a soft convergence from circuit-switched services to the switching packet world. The IMS can unify access to multiple technologies and equipment-based IP. Indeed, the heterogeneity of access and technology imposes a challenge or repercussion in QoS, mobility and security. The article focuses on the importance of security, and it proposes a conceptual analysis on existing standards. Finally we propose an approach that meets the needs of a network such as IMS. The study focuses the main interfaces of IMS and security around and inside network with a sensitive context.

The security in IMS network is a big challenge for both users and service providers over IMS. Many research works are interested in this field to build more secure networks and to deal with security problems. This paper aims to present firstly a synthesis of the most important existing model used to secure IMS network. Secondly, the paper introduces our approach to address security in IMS. This approach defines light model for IMS network, identifies and focuses in the most vulnerable components of IMS network. It gives more importance to secure these components in order to build a safety network.