The Session Initiation Protocol (SIP) is commonly used to establish Voice over IP (VoIP) calls. Mostly recently, Yoon et al. proposed a new secure and efficient SIP authentication scheme in a converged VoIP network based on ECC. In this paper, we first demonstrate that the recently proposed SIP authentication scheme is insecure against off-line password guessing attacks. Thereafter, we propose ...

Es wird eine Vorgehensmethodik für eine strategische Informatikplanung (SIP) beschrieben, die in der Schweiz von der Bundesverwaltung als Grundlage für die strategische Informatikplanung in allen Departementen und Verwaltungseinheiten vorgegeben ist [SIP-Bund 2003]. Die betrachtete Methode orientiert sich im Wesentlichen an folgenden Grundsätzen: ❏ Informatik ist ein Werkzeug von strategischer ...

The steady improvements in the networking infrastructure and ever increasing broadband penetration has fueled the resurgence of voice-over-IP (VoIP). One of the important contributors to this growth has also been the development and wide acceptance of the session initiation protocol (SIP). However, the current usage of SIP requires a per-application deployment (each application using its own SI...

The popularity of gateways that interwork between the PSTN (Public Switched Telephone Network) and SIP networks has motivated the publication of a set of common practices that can assure consistent behavior across implementations. This document taxonomizes the uses of PSTN-SIP gateways, provides uses cases, and identifies mechanisms necessary for interworking. The mechanisms detail how SIP prov...

The objectives of this study were to investigate the immune enhancement activity of the Sarcodon imbricatus polysaccharide (SIP). In this study, water extraction method was employed to isolate polysaccharides from the Sarcodon imbricatus. The immunoloregulation effects of SIP were evaluated with models of cyclophosphamideinduced mouse immunosuppression. The immunoloregulation activities of SIP ...

Session Initiation Protocol (SIP) was standardized for real-time applications and extended to support terminal mobility by Internet Expert Task Force (IETF). However, SIP terminal mobility suffers from the considerable handoff latency which is unsuitable for the real-time communications. In this paper, we propose Predictive Address Reservation with SIP (PAR-SIP) which decreases handoff delay by...

The rapid development of services provided on SIP networks not only define the necessity of creating new equipment and standards but also requires the development of new methods and programming software tools for modeling and analyzing the effectiveness of the overload control mechanisms in SIP-server networks. The modeling process utilizes mathematical and simulation models as well as simulato...

Today, the session initiation protocol (SIP) is the predominant protocol for Voice-over-IP (VoIP) signalling. The intention of this paper is to present an overview of VoIP security issues both current and future – focusing on SIP. We start by presenting some fundamental differences between VoIP and the public switched telephone network (PSTN). We then look at specific problems for SIP signallin...