The first step for the integration of multimedia traffic within the Internet is the provision of voice services, both traditional POTS (Plain Old Telephony Services) and innovative, like multi-party audio conferences or high quality audio. Voice services in Internet are broadly indicated as VoIP (Voice over Internet Protocol), including all possible services that can be built on vocal interacti...

Today Voice over Internet Protocol (VoIP) is used in large scale to deliver voice and multimedia over the packet data networks, such as the Internet. The Session Initiation Protocol (SIP) is widely used as a signalling protocol for VoIP. As SIP is being used more, the security of it is an important issue. In this paper, we concentrate on user authentication in SIP. We examine current solutions ...

The recent widespread deployment of wireless LAN technology raises the question of how a mobile telephony system might instead be architected to use wireless LAN access points and the Internet to achieve similar services. In this paper, we examine an end-to-end architecture for mobile telephony, with a strong focus on endpoint issues. We have designed, implemented, and have experience using dev...

Internet telephony has had a tremendous impact on how people communicate. Many now maintain contact using some form of Internet telephony. Therefore the motivation for this work has been to address the quality aspects of real-world Internet telephony for both fixed and wireless telecommunication. The focus has been on the quality aspects of voice communication, since poor quality leads often to...

— Convivo is a VoIP system designed to provide reliable voice communication for poor quality networks, especially those found in rural areas of the developing world. Convivo introduces an original approach to maintain voice communication interaction in the presence of poor network performance: an Interface-Adaptation mechanism that adjusts the user interface in order to reduce the impact of hig...

This paper surveys packet loss in Voice over Internet Protocol (VOIP). The voice quality is affected by many network impairments. IP networks are on a steep slope of innovation that will make them the long term carrier of all types of traffic, including voice. Such networks are not designed to support real time voice communication because of their variable characteristics. The conversational qu...

The Voice over IP (VOIP) and the IP based internet services are revolutionizing the way wireless networks are developed. The VOIP services make use of the internet backbone rather than the traditional circuit based networks (PSTN and the wireless voice services). The advantage provided by the VOIP technology over the traditional circuit based networks is that both voice and data signals are tra...

An Internet telephony system is basically a computer-form of a conventional telephone to support real-time voice communication between two or more users who are connected to the Internet. Internet telephony circumvents expensive international telephone toll charges by using Internet as an intermediary medium to transport voice signals between two users. In doing so, transcontinental telephone c...

The popular press often extolls packet networks as much more efficient than switched voice networks in utilizing transmission lines. This impression is reinforced by the delays experienced on the Internet and the famous graphs for traffic patterns through the major exchange points on the Internet, which suggest that networks are running at full capacity. This paper shows the popular impression ...