Performance of SIP servers doesn’t seem to gain much focus. Developers usually focus on implementation of new features that not standardized yet. Our goal was to develop a high performance SIP server that will be flexible and efficient. Result is the SIP Express Router, fast and efficient SIP proxy server. We briefly describe basics of SIP, then we describe architecture of the server and performance optimizations. Finally we present an overview of bottlenecks in the SIP protocol that make the performance tuning much harder.

interactive voice response applications that are accessible from telephones as well as IP phones. We also describe how we have used sipvxml in our multi-party multimedia conferencing server. We propose other applications and extensions that can benefit from this technology in our IP telephony test bed. (keywords: Internet telephony; interactive voice response; SIP; VoiceXML; sipvxml) I.

We describe the architecture and implementation of our comprehensive multi-platform collaboration framework known as Columbia InterNet Extensible Multimedia Architecture (CINEMA). It provides a distributed architecture for collaboration using synchronous communications like multimedia conferencing, instant messaging, shared web-browsing, and asynchronous communications like discussion forums, shared files, voice and video mails. It allows seamless integration with various communication means like telephones, IP phones, web and electronic mail. In addition, it provides value-added services such as call handling based on location information and presence status. The paper discusses the media services needed for collaborative environment, the components provided by CINEMA and the interaction among those components.

Abstract: This paper reviews the IETF proposed enhancements to the Session Initialisation Protocol (SIP) to prevent the abuse of its implementation in Voice-over-IP (VoIP) communication services. We look at some of the benefits and drawbacks of these proposed enhancements to ensure trustworthy SIP message exchange. Many proxies assist in establishing of a SIP session. These proxies may modify the traversing SIP messages during transit by injecting routing, logging and call control headers. Due to the distributed nature of VoIP, this could have various implications. We highlight these and proposes a new mechanism of certifying these changes, allowing communicating parties to audit the committed changes. Our aim is to compliment the suggested enhancements to further secure SIP communication.

The public switched telephone network (PSTN) provides ubiquitous availability and very high scalability of more than a million busy hour call attempts per switch. If large carriers are to adopt Internet telephony, then Internet telephony servers should offer at least similar quantifi-able guarantees for scalability and reliability using metrics such as call setup latency, server call handling capacity, busy hour call arrivals, mean-time between failures and mean-time to recover. This thesis presents a reliable, scalable and interoperable Internet telephony architecture for user registration, call routing, conferencing and unified messaging using commodity hardware. The results extend beyond Internet telephony to encompass multimedia communication in general. The architecture presented in this thesis deals with two aspects: at least PSTN-grade re-liability and scalability of the Internet telephony servers, and interoperable Internet telephony services such as conferencing and voice mail using existing protocols. We describe the archi-tecture and implementation of our Session Initiation Protocol (SIP)-based enterprise Internet telephony architecture known as Columbia InterNet Extensible Multimedia Architecture (CIN-EMA). It consists of a SIP registration and proxy server, a multi-party conferencing server, a gateway for interworking SIP with ITU’s H.323, an interactive voice response system and a

For at least the next decade, we foresee two classes of packet communication networks existing side-byside and dominating the data communications scene: