<span lang="en">IP Multimedia Subsystem (IMS) is becoming the prevailing candidate for managing future mobile multimedia communications, including critical communications such as public safety, emergency professionals and corporate networks. IMS security and privacy has gained much attention in the few last years. The review of recent IMS security activities stresses the inclusion of intermediate nodes in the media path of secured communications as an open issue. This paper presents an end-to-middle-to-end solution which enables the usage of IMS media plane elements such as recorders, transcoders and novel cross-ciphering functions in a secure way. The proposed solution, which is fully compliant with IMS, includes the network architecture, the signaling plane for session signaling and key management, and the media-plane security characteristics. Experimental results demonstrate that the proposed solution can provide media interoperability (both transcoding and cross-ciphering) with a cost of 17% overhead to a standard IMS call setup in the signaling plane.</span>

<span lang="en">Emergency telecommunication systems play an important role in people's daily life, supporting communication for the public and first responders during emergency related incidents. Nonetheless, the majority of existing emergency communications are limited to traditional voice and text message services due to the data bandwidth constraint of current networks. It is well known that emerging 4G broadband communication technologies have the ability to provide a range of multimedia services (e.g. picture transmission) that could be utilised by the emergency services to save lives. However, a secured emergency conversation cannot be established between incompatible mobile/end devices without the assistance of a security gateway. Therefore, this paper proposes a technology independent security gateway that provides security support for future emergency telecommunication systems. The proposed security gateway works in three modes to cover all the situations in which its assistance is required to establish a secured emergency conversation. In addition, the development process of the security gateway will also be fully discussed in this paper.</span>