Advanced IMS client supporting secure signaling

With recent advances in core and access networks and theavailability of increased bandwidth and sophisticated devices forend users, there is an increased demand for client applicationsrunning on mobile devices, such as laptops and handheld devices, tosupport real time applications like Voice over Internet Protocol(VoIP) and streaming video, apart from traditional applicationslike web browsing. This paper presents a prototype IP MultimediaSubsystem (IMS) client, which serves as a VoIP client to set upcalls between Internet Protocol (IP) devices and interworks withcircuit-switched networks to deliver calls to public switchedtelephone network (PSTN) phones. It implements supplementaryservices (including call waiting, call transfer, and callforwarding); supports multimedia ringing, short messageservice-multimedia messaging service (SMS-MMS), audio-videoconferencing, and peer-to-peer video; and it can deliver a call toa user (as opposed to a device) by simultaneously ringing multipledevices registered by the user. Further, to address varioussecurity concerns, the client supports Hypertext Transfer Protocol(HTTP) digest authentication using Message Digest 5 (MD5)cryptographic function authentication and key agreement (AKA) andcan create secure tunnels to the core network using IP security(IPsec). © 2008 Alcatel-Lucent.