As current Voice-over-IP (VoIP) systems encourage a direct communication between the callees they are similar in design to peerto-peer (P2P) approaches. Therefore, we introduce a framework to build distributed supplementary services for VoIP. Some of these services like completion of calls on no reply or holding are already commonly established in public switched telephone networks or realized ...

We present a survey of Voice over IP security research. Our goal is to provide a roadmap for researchers seeking to understand existing capabilities and, and to identify gaps in addressing the numerous threats and vulnerabilities present in VoIP systems. We also briefly discuss the implications of our findings with respect to actual vulnerabilities reported in a variety VoIP products.

The rapid evolution of voice and data technology is significantly changing the business environment. The introduction of services such as instant messaging, integrated voice and email, and follow me services has contributed to a work environment where employees can communicate much more efficiently, thus increasing productivity. To meet the demands of the changing business environment businesse...

In this paper, we address issues related to implementing Voice-over-IP (VoIP) services in packet switching networks. VoIP has been identified as a critical real-time application in the network QoS research community and has been implemented in commercial products. To provide competent quality of service for VoIP, the call admission control (CAC) mechanism has to be introduced to prevent packet ...

In this paper, we present a framework for the analysis of a set of adaptive variable-bit-rate voice sources in a packet network. The instantaneous bit rate of each source is determined by an end-to-end control mechanism that, based on measurements of packet delay and loss rate, selects the rate that best matches current network conditions. Several such algorithms can be analyzed with the propos...

We propose multi-stream transmission of real-time voice over best-effort packet networks such as today’s Internet, where multiple redundant descriptions of the voice stream are sent over independent network paths. At the receiver, multi-stream adaptive playout scheduling is employed to improve the tradeoff among delay, late loss rate, and speech quality. Experiments over the Internet suggest la...

There have been a small number of cost studies of Voice over IP (VoIP) in the academic literature. Generally, they have been for abstract networks, have not been focused on the public switched telephone network, or they have not included the operating costs. This paper presents the operating cost portion of our ongoing research project comparing circuit-switched and IP network costs for an exis...

Skype is a Peer-to-Peer (P2P) Voice over IP (VOIP) chat program. It provides its clients with an inexpensive means to communicate worldwide via the internet through wired and wireless networks. In the past this application was limited strictly to computers, yet with continuous advancements in mobile communication, Skype phones and other mobile devices have recently hit the market in an attempt ...

not my own work has been identified and no material is included for which a degree has previously been conferred. Abstract When using Voice over IP (VoIP) in Wireless Mesh Networks the overhead induced by the IEEE 802.11 PHY and MAC layer accounts for more than 80% of the channel utilization time, while the actual payload only uses 20% of the time. As a consequence, the Voice over IP capacity i...