VoIP Technology Research Articles

Tool assisted H.323 dial‐plan design following formally defined strategies

AbstractThis paper considers H.323 v4 VoIP networks consisting of gateways and gatekeepers, addressing the task of terminating calls to multiple ISDN networks. Our goal is the maximal utilization of the gatekeeper's centralized routing mechanism for call termination to ISDN networks based on load balancing and resource availability indication (RAI), thus minimizing the need for usage of unwanted (second attempt) overflow mechanisms. We elaborate on the drawbacks of overflow mechanisms and give an overview on different solutions offered in practice by vendors. The discussion justifies the emphasis on load balancing, thus we present an algorithm and tool assisted approach for the systematic assignment of PRIs from ISDN networks to gateways. We follow strictly defined design criteria that lead to an optimized network dial‐plan. We thus offer a stand alone, off‐line solution without the need of any extra add‐ons or upgrades. This is intended to replace the purely intuitive approach followed by today's planners.Our scope is the design rather than the runtime environment; the latter continues to feature the simplicity of a single global RAI per gateway. We consider desirable and non‐desirable link distribution topologies between gateways and ISDN networks based on operational and economic evaluation criteria. These measure the number of ‘wasted’ gateway ports or ‘inappropriately’ allocated network interfaces. Our approach is illustrated through a worked out example showing key features of the proposed algorithm and revealing characteristic cases met in the ISDN interface allocation.Finally, we show how the presented methodology, which presently addresses a H.323 design issue, can provide performance benefits in the VoIP technologies of the immediate future. Copyright © 2005 John Wiley & Sons, Ltd.

VoIP Technology? Its Current Status and Problems

VoIP Technology? Its Current Status and Problems

Speaking of Wi-Fi

Big organisations are realising that their wireless networks can be used for more than just data traffic. Businesses have long recognised the benefits of being able to keep in touch with employees on the move. On the face of it, the arrival of Wi-Fi provides a straightforward cost-effective solution capable of building on VoIP and wireless local area network (WLAN) technology to provide workers with the sort of communications mobility that they take for granted just about everywhere else in their daily lives. Networks that allow staff to roam with their office phone across a whole organisation are an enticing prospect, but quality of service and security are still important issues.

International Standards for VoIP

The advent of VoIP technology has created unique opportunities to move to network structures that demonstrate a potentially lower cost per unit, exhibit more flexibility in terms of the services they can support and fully embrace multimedia applications. Yet, without common industry-accepted methods of providing and controlling communications traffic, these benefits are unlikely to be realised to the fullest extent possible. Appropriate standards specifications are therefore vital for enabling VoIP services on a global scale. This paper explains why international standards are needed for VoIP, gives a brief survey of the more important standards activities, and highlights some current issues that need to be addressed by the standards community.

Evaluating VoIP Technology — Technology Push/Market Pull

With many raised expectations of what it will offer, voice over IP has enjoyed a high profile in the communications industry. However, in common with any emerging technology, the reality of the functionality that available equipment can deliver is often at variance with such expectations. This paper highlights the role of technology assessment in refining VoIP products and highlights the value of such activities from a number of perspectives. It describes an approach to evaluate VoIP solutions, the problems associated with the testing of VoIP networks and network components, and the tools and techniques employed to do so. The paper also outlines the capabilities of the BTexaCT VoIP technology evaluation test bed, and example case studies of detailed evaluation and testing.

Teaching of Telecommunication-Specific University Course in Cooperation with Partners from Industry

Modern information and telecommunication technology (ICT) is rapidly evolving in time and there is a constant need for specialists, who have good knowledge to meet the industry needs. One way to perform industry specific knowledge transfer form industry to academia is to involve partner's specialist in teaching the courses. The aim of this paper is to introduce an example of course setup in teaching VoIP and IMS technologies for ICT students. We analyze the opportunities and limitations seen in organizing and teaching this course based on our 3-year experience. We also give some suggestions for developing the course when industry interest and support, due to the situation in economy and market, may change in time. Bibl. 3 (in English; abstracts in English and Lithuanian).http://dx.doi.org/10.5755/j01.eee.110.4.306