As the Internet evolves into a ubiquitous communication infrastructure and provides various services including telephony, it will be expected to stand up to the toll quality standards set by traditional telephone companies. Our objective in this paper is to assess to what extent today’s Internet is meeting this expectation. Our assessment is based on delay and loss measurements taken over wide-...

Supporting mobility in real-time applications such as Internet telephony is in demand as mobile Internet becomes prevalent. A simple solution is to use Mobile IP in order to provide transparent handoffs to upper layer applications. However, due in part to the Mobile IP’s limitations such as triangular routing delay and encapsulation overhead, application-layer solutions for mobile Internet tele...

Voice over Internet Protocol (VoIP) is a form of voice communication that uses audio data to transmit voice signals to the end user. VoIP is one of the most important technologies in the World of communication. Around, 20 years of research on VoIP, some problems of VoIP are still remaining. During the past decade and with growing of wireless technologies, we have seen that many papers turn thei...

The presence of voice-over-IP traffic in the Internet is constantly increasing, as it offers improved connectivity and quality-of-service comparable to classical telephony at costs that the rival circuit-switched telephony systems cannot match. This paper evaluates the audio quality of voice-overIP calls that use the Datagram Congestion Control Protocol (DCCP), a congestion-controlled alternati...

Internet Telephony is realized by way of instant messaging and the transmitted data are voice rather than text packets, therefore it is more difficult to identify and/or prevent Spam over Internet Telephony (SPIT) than SPAM  junk e-mail. With the rising popularity of Voice over IP (VOIP), SPIT becomes a serious issue on security nowadays. This paper proposed an effective SPIT defense system, w...

Voice over Internet Protocols (VoIP) is an IP-based communication technology or commonly known as (IP). In which, IP currently widely used for mobile activities. However, the main concern in application of VoIP system ability to maintain information confidentiality while guaranteeing protection its primary users. For this reason, it requires do addition Virtual Private Network (VPN) features. C...

In this thesis, we focus on large scale Voice over IP (VoIP) deployment over heterogeneous Internet environments. We first present an overview of VoIP coding and transmission mechanisms. Then, we investigate performance limitations in the case of a large number of VoIP flows transported over wired Internet links between peer VoIP gateways. We address, in the first part of the thesis, the need t...

WiMAX is a wireless broadband access technology which provides high data rates, long coverage and IP based connectivity to the stationary as well as mobile users. Voice over Internet Protocol (VoIP) through WiMAX is found to be very promising. In this paper, simulative investigations have been done to identify the suitable voice codec for the same. In doing so, silence suppressed voice signal a...