0140-3664/$ see front matter 2008 Elsevier B.V. A doi:10.1016/j.comcom.2008.03.016 * Corresponding author. Tel.: +49 30 3463 7378; fa E-mail addresses: [email protected] fraunhofer.de (G. Zhang), [email protected] (D. Gen (G. Kambourakis), [email protected] (T. Dagiuklas), jiri. [email protected] (D. Sisalem). The emergence of Voice over IP (VoIP) has offered numerous advantag...

This paper proposes an integrated mobility scheme that combines the procedures of fast handover for Mobile IPv6 (FMIPv6) and session initiation protocol (SIP) mobility for realtime communications. This integrated approach is based on the context of the applications utilized. Furthermore, to reduce system redundancies and signaling loads, several functionalities of FMIPv6 and SIP have been integ...

Current Voice over IP (VoIP) and Instant Messaging (IM) systems follow a client-server model, or require clients and network elements supporting non-standard protocols. In this paper, we present a standards-based, fully decentralized peer-to-peer (P2P) communications system. This system can be used in situations where constant Internet connectivity is not possible, and supports ad hoc, ephemera...

The Session Initiation Protocol (SIP) is the main protocol behind Voice over IP (VoIP). However, it does not provide authentication, which may lead to possible impersonation and eavesdropping threats. Negotiating keys using digital certificates may help secure the channel, but this method incurs extra maintenance cost. Verbal authentication utilizes the real-time nature of VoIP but it requires ...

Voice-over-Internet protocol (VoIP) is an emerging technology that is beginning to replace traditional telephone services because it is much more cost effective for the consumer and businesses. Long distance charges are relatively a thing of the past, and in general there are more feature-rich services available over a VoIP line than traditional phone services. VoIP provides phone services with...

Mobile Voice over IP (Mobile VoIP) allows mobile users to continuously talk with each others while roaming across different networks. In such wireless application, it is vulnerable to information security. In this paper, we present two efficient and secure authentication protocols for mobile VoIP services. In our approaches, we first develop a secure authentication protocol for mobile IP regist...

Contemporary Voice-Over-IP (VoIP) systems typically negotiate only one codec for the entire VoIP session life time. However, as different codecs perform differently well under certain network conditions like delay, jitter or packet loss, this can lead to a reduction of quality if those conditions change during the call. This paper makes two core contributions: First, we compare the speech quali...

The session initiation protocol is one the most popular protocols that is used in Internet protocol multimedia subsystems and adopted by a wide range of networking vendors. This research suggests a secure distributed session initiation protocol-based architectural model that can be deployed in service provider data centers to maintain the service availability, scalability, and security. This re...