Despite recent advances in Computer Telephony (CT) and IP Telephony (IPT) standards at defining flexible architectures to support new technologies, the current CT paradigm does not adequately support the requirements of advanced spoken dialogue systems. This paper describes an application framework based on CT and IPT standards that defines new architectural components for information access, a...

As broadband and high-speed IP networks spread, IP-telephony services have become a popular speech communication application over IP networks. Recently, the speech quality of IP-telephony services has become close to that of conventional PSTN services. To provide better speech quality to users, speech communication with wider bandwidth (e.g., 7 kHz) is one of the most promising applications. To...

A new, lightweight security mechanism for the PSTN-VoIP hybrid networks is described. It is based on the two informationhiding techniques: audio watermarking and network steganography. The proposed scheme is suitable especially for the PSTN-IP-PSTN (toll-by-passing) scenario, which nowadays is a very popular application of the IP Telephony systems. Proposed mechanism can be used to authenticate...

In this paper we describe a new, lightweight security mechanism for PSTN-VoIP cooperation that is based on two information hiding techniques: digital watermarking and steganography. Proposed scheme is especially suitable for PSTN-IP-PSTN (toll-by-passing) scenario which nowadays is very popular application of IP Telephony systems. With the use of this mechanism we authenticate end-to-end transm...

Introduction Voice over IP (VoIP) has been characterised as the largest change to the telecommunication industry since the introduction of the Global System for Mobile Communication (GSM) 10 years ago. This statement is partly wrong. VoIP could be deployed as an alternative way to provide telephony with very little impact on the user experience. However, VoIP is an element of the transition fro...

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...

Multicasting has become increasingly important with the emergence of Internet-based applications such IP telephony, audio/video conferencing, distributed databases and software upgrading. IP Multicasting is an efficient way to distribute information from a single source to multiple destinations at different locations. In practice IP is considered as a layer 3 protocol. Multiprotocol label Switc...

The quality of audio in IP telephony is significantly influenced by various factors, including type of encoder, delay, delay variation, rate and distribution of packet loss, and type of error concealment. Hence, the performance of IP telephony systems is highly dependent on understanding the contribution of these factors to audio quality, and their impact on adaptive transport mechanisms such a...

Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) are two switching technologies that are being used (or proposed) for large-scale integrated services networks. Integrated services networks are designed to support real time services, such as telephony as well as data services. Both technologies have the potential to radically change the economics and operations of telephone services. ...

Although the Internet was designed to handle non-real time data traffic, it is being used increasingly to carry voice and video. One important class of contributors to this growth are Internet telephones. Critical to more widespread use of Internet telephony is smooth interoperability with the existing telephone network. This interoperability comes through the use of Internet Telephony Gateway’...