We discuss the technical viability of transporting real-time voice over IP networks when the output rate of the speech encoder is adjusted to match the characteristics of the network: speech is coded at low bit rates when the network is congested; at higher bit rates, otherwise. First, issues affecting perceptual QoS are analyzed. The rationale for Adaptive Voice over IP (AVoIP) is explained an...

30 years ago PABX systems were compromised by hackers wanting to make long distance calls at some other entities expense. This activity faded as telephony became cheaper and PABX systems had countermeasures installed to overcome attacks. Now the world has moved onto the provision of telephony via broadband enabled Voice over Internet Protocol (VoIP) with this service now being provided as a rep...

We discuss techniques for Voice Activity Detection (VAD) for Voice over Internet Protocol (VoIP). VAD aids in saving bandwidth requirement of a voice session thereby increasing the bandwidth efficiently. In this paper, we compare the quality of speech, level of compression and computational complexity for three time-domain and three frequency-domain VAD algorithms. Implementation of time-domain...

Voice over IP (VoIP) service is expected to play a key role to new ways of communication. It takes advantage of Internet Protocols by using packet networks to transmit voice and multimedia data, thus providing extreme cost savings. On the other hand, this technology has inherited drawbacks, like SPAM over Internet Telephony (SPIT). A well-established method to tackle SPIT is the use of CAPTCHAs...

We discuss techniques for Voice Activity Detection (VAD) for Voice over Internet Protocol (VoIP). VAD aids in reducing bandwidth requirement of a voice session thereby using bandwidth efficiently. Such a scheme would be implemented in the application Layer. Thus the VAD is independent of the lower layers in the network stack [3]. In this paper, we compare four time-domain VAD algorithms in term...

Over the last few years, a rapidly increasing number of Internet-of-Things (IoT) systems that adopt voice as the primary user input have emerged. These systems have been shown to be vulnerable to various types of voice spoofing attacks. However, how exactly these techniques differ or relate to each other has not been extensively studied. In this paper, we provide a survey of recent attack and d...

This paper describes the design, implementation and deployment of Lyceum, a groupware system providing students and tutors with real time voice conferencing and visual workspace tools, over the standard internet. Lyceum uses a Java client/server architecture to tackle a formidable set of networking requirements: multi-way voice communication with synchronous shared displays, scalable to hundred...

This paper describes the design, implementation and deployment of Lyceum, a groupware system providing students and tutors with real time voice conferencing and visual workspace tools, over the standard internet. Lyceum uses a Java client/server architecture to tackle a formidable set of networking requirements: multi-way voice communication with synchronous shared displays, scalable to hundred...

The speech of the Voice over Internet Protocol (VoIP) system is degraded by network layer problems which include delay, packet loss and jitter. The implementation of signal through digital signal processor can improve the quality of degraded VoIP signal. The work in this paper presents the comparison of speech quality for narrowband and wideband VoIP using TMS320C6713 DSP processor. The VoIP si...

This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Abstract This document defines the expected behaviour of a client to various aspects of a Voice Profile for Internet Mail (VPIM) message or any voice and/or fax message.