Voice OVER IP (VOIP)

International Journal of Computer Applications, 2016

Voice over Internet protocol (VoIP), which is a communication protocol existing over a network. The IP network can makes it possible for users to make telephone calls using the VoIP technology. Use of VoIP and Internet telephony has increased significantly in the recent years. These new phone services are based on the transmission of voice over packet switched IP networks. VoIP can be realized on any data network that uses IP, like the Internet, Intranets and Local Area Networks (LAN). VoIP customers use their Internet connection to connect to the Internet as well as to make phone calls. VoIP is the real-time transfer of voice signals using the Internet Protocol (IP) over the Internet or a private network. In simpler terms, your voice is converted to digital signal by VoIP that travels over the internet. The key factors that entice enterprises to switch to VoIP are its flexibility and cost efficiency. Some security problems may arise due to the widespread deployment of VoIP. Voice over IP (VoIP) has the potential to provide interactive communication services like video and voice conferencing. VoIP helps to transfer data which are difficult to transfer over circuit-switched wired and wireless networks.

Voice over Internet Protocol (VoIP) is perceived as the best example of collaboration technology in today’s telecommunication space. There have being a paradigm shift from regular legacy telephone systems to VoIP over the last decade by most telecommunication and multinational companies globally. One of the huge benefit of VoIP is noticeable reduction in international call rates. In addition to the potential cost savings, VoIP offers the prospect of integrating voice with data and video applications, this goes a long way in increasing workers’ productivity within organizations. Many organizations are already embracing VoIP as replacement for their legacy PBX, others are integrating the existing PBX system with VoIP. This write up will focus on deployment of PBX-VoIP converged solution in enterprise organizations, where cost saving is one of the primary objectives

Voice over Internet Protocol (VoIP) has been widely deployed since the integration of the voice and data networks reduces management effort and cost. Since VoIP share the same infrastructure with traditional data network, it inherits all security problems from data network. Furthermore, VoIP also has its own security problems coming from new protocols and network component. This paper focuses on these VoIP specific security threats and the countermeasures to mitigate the problem. At first, this paper gives a brief introduction of VoIP techniques: the network structure, network components, protocols and standards, data handling procedures, quality of service requirements. Secondly, the paper discusses the VoIP specific security threats using the principle of CIA (Confidentiality, Integrity and Availability). The countermeasure to mitigate these threats is also discussed. At last, the paper proposes the practice to secure VoIP networks.

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2013

Voice over IP (VoIP) is an emerging communication service allowing voice transmission over a private or a public IP network. VoIP allows significant benefits for customers and service providers including cost savings, phone and service portability, mobility, and the integration with other applications. Nevertheless, the deployment of the VoIP technology encounters many challenges such as interoperability issues, security issues, and QoS concerns. Among these disadvantages, QoS issues are considered the most serious due to the QoS problems that may arise on IP networks, and the stringent QoS requirements of voice traffic. The aim of this paper is carry out a deep analysis of the QoS concerns of the VoIP technology. Firstly, we present a brief overview about the VoIP technology. Then, we discuss the QoS issues related to the use of the IP networking technology for voice traffic transmission. After that, we present the QoS concerns related voice clarity. Finally, we present the QoS mechanisms proposed to make the IP technology able to support voice traffic QoS requirements in terms of voice clarity, voice packet delay, packet delay variation, and packet loss.

Telecommunications in recent years has been undergoing a rapid growth all over the world. Prominent among the advancements of telecommunication is the evolution of modern converged network that provides the trio of data, voice and video network on a single network platform. The converged technology uses the internet as a medium to transmit data, voice and video packets using packet switching. This comes with numerous benefits by providing add-ons to both the service providers and users. The VoIP technology has been widely accepted and has received a boost in most western countries like the US and UK where users are now migrating from the legendry Public Switch Telephony Network (PSTN) to VoIP because of the numerous benefits it offers but unfortunately the business environment in Nigeria is yet to key into this promising technology. This study therefore focuses on introducing and implementing this technology in a converged network in Nigerian environment. It will also showcase VoIP’s numerous advantages and look at issues likely to be encountered during its implementation. It is hoped that it will help to serve as a tool in decision making process by converging the VoIP network with the already available data network.

The internet has been undergoing rapid and continuous growth over the past few years. The most significant development the telecommunication industry has witnessed is the evolution of Voice over IP technology. This technology uses the internet as a medium for transmitting voice during a telephone conversation between two or more parties. VoIP technology comes with numerous benefits like reduced call cost and wide variety of add-ons to both the service providers and the end users. Despite all these, the technology is subjected to security risk because of the open nature of the internet. Much emphasis has been placed on the quality of service of VoIP over the years and dark eyes have been turned on its security. This study therefore aims to identify the security threats and attack VoIP can be exposed to during transmission, produce a VoIP system using the open source Asterisks before securing the network using IPSec VPN

2008

Since the late 90's IP telephony, commonly referred to as Voice over IP (VoIP), has been presented as a revolution on communications enabling the possibility to converge historically separated voice and data networks, reducing costs, and integrating voice, data and video on applications. This paper presents a study over the standard VoIP protocols H.323, session initiation protocol (SIP), media gateway control protocol (MGCP), and H.248/Megaco. Given the fact that H.323 and SIP are more widespread than the others, we focus our study on them. For each of these protocols we describe and discuss its main capabilities, architecture, stack protocol, and characteristics. We also briefly point their technical limitations. Furthermore, we present the advanced multimedia system (AMS) project, a new system that aims to operate on Next Generation Networks (NGN) taking the advantage of its features, and it is viewed as the successor to H.323 and SIP.

IEEE Communications Magazine, 2001

Voice over IP services have recently emerged as a low-cost alternative to PSTN voice service, and an attractive solution for voice/data integration in public and private networks. Satellite systems, as an integral part of the global communications infrastructure, already have an increasing portion of their capacities used to carry data packets, and with their global coverage and reach to remote areas are well positioned to enable growth of VoIP services. For VoIP over satellite, several issues need to be addressed. These include transmission and quality of service issues, as well as service-related issues such as service creation and customization, support of IN and supplementary services, and seamless integration with the PSTN. While the service-related aspects of VoIP are common to both terrestrial and satellite networks, transport-related issues are different. This article reports performance results of laboratory experiments for evaluating VoIP over satellite under different link and traffic conditions. To avoid congestion which will lead to a large number of packets being dropped in routers and result in a severe degradation of voice quality, care should be taken to ensure that the link loading level does not exceed the link capacity.