In this paper, we provide an analytical model for the performance study of different structured P2P overlay networks used for lookup service in IP telephony systems. The overlay provides an infrastructure for the lookup service required before an actual voice communication is initiated. Our model captures the performance behavior of such overlays including the mean session set-up delay of a cal...

Research on email, voicemail, and instant messaging highlights the extent to which conversations often consist of multiple messages exchanged over a fairly extended period of time, using more than one communication medium. This research in progress explores the impact of increasing availability and integration of communication tools on media switching practices, which is the act of changing med...

Traffic transmission over the radio channel requires appropriate techniques to preserve information integrity while maintaining the desired QoS and energy constraints. In this paper, we focus on a possible configuration of the ARQ protocol defined in 3GPP (Third Generation Partnership Project) technical specifications. A Markov model is developed in order to study the protocol behavior as chann...

executive system” controlling the telephony network. One concern about the SPIRITS work is that consensus has been hard to reach within the working group and hence progress to date has been slow. At the time of writing, these issues seem to have been dealt with and the pace of work seemed to be accelerating. Whatever the progress of IETF work on SPIRITS, a number of commercial implementations o...

Voice over IP (VoIP) is rapidly changing the way we use the telephone for voice communications. The term "Voice over IP" defines the transport of VoIP‐based networks, including the signaling and streaming protocols as well as describing the codecs. VoIP is widely used by all kinds of consumers ranging from computer enthusiasts who are excited to get free long‐distance calls over the Internet to...

Voice-over-DSL (VoDSL) technology provides a major boost to competition in local telephony market by greatly reducing the cost of local access. VoDSL leverages the high-speed transmission of DSL technology to deliver multiple telephony circuits plus high-speed data over a single loop. Although the data services delivered over xDSL are usually IP-based, native ATM is the ideal technology choice ...

The purpose of this white paper is to illustrate the flexibility and benefits of the Simple Gateway Control Protocol Interactive Control Panel (S-ICOP) for testing Voice over IP Network Gateways, Announcement Servers, and Internet Call Routing (ICR) node employed in an IP Telephony network architecture. Some relevant test configurations are shown and the generic high-level test categories that ...

Recent Voice over Internet Protocol (VoIP) technology is attracting more and more attention and interest in the industry. VoIP applications such as IP telephony systems involve sending voice transmissions as data packets over private or public IP networks as well as reassembled and decoded on the receiving side. Security concerns are always the major barrier that prevents many businesses from e...

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...