Analysis of the quality of experience of a commercial voice-over-IP service

Voice-over-IP (VoIP) services, enabling users to make cheap phone calls using the Internet, are becoming increasingly popular, not only on desktop computers but also on mobile devices such as smartphones that are connected through mobile networks. Users' perception of the level of quality plays a key role in making a VoIP service to succeed or to fail. This paper demonstrates the influence of technical parameters (such as the audio codec, type of data network, and handovers during the call), device characteristics (such as the platform, manufacturer, model, and operating system), and application aspects (such as the software version and configuration) on the subjective quality of a commercial VoIP service. The relative influence of all these parameters is determined and a decision tree combines these results in order to assess the subjective quality. Combining a large number of objective parameters in a decision tree to determine the user's subjective evaluation of the quality of a VoIP call is a novel and complex procedure. The subjective quality, in turn, has an influence on the duration of the call, and as a result an influence on the usage behavior of the service. The users' assessment of the service quality is not evaluated by merely taking a snapshot of the perceived quality at one moment in time but rather by analyzing the perceived quality over a longer period of time during service usage, which has not been done up to now. Analyzing the VoIP service using a regression analysis over a period of 120 days showed that the perceived quality decreases slightly when the user utilizes the service more often and gets more familiar with it

A comprehensive IVR (Interactive Voice Response) analysis model using online analytical processing (OLAP) on a multidimensional data cube

Private Branch eXchange (PBX) is a tool indispensable in the business world. The telephone exchanges allow employees to perform internal connections between telephones, or make calls to the external network also known as Public Switched Telephone Network (PSTN). With increasing Internet usage, there is interest in understanding what services are offered. Enterprise Courier is a commercial Internet Protocol Private Branch eXchange (IP PBX) based on open source Asterisk web-based PBX software for Linux, which supports multiple protocols and services, like Interactive Voice Response (IVR). Cisco Unified Communications Manager (CUCM) or CallManager, is a software based call-processing system (IP PBX) developed by Cisco Systems. CUCM tracks all active Voice over IP (VoIP) network components; including phones, gateways, conference bridges, among others. IVR is part of the Academic Services costumer contact and ticketing of University of Beira Interior (UBI). IVR monitoring and analysis are essential for effective operation and resource management, in particular, multidimensional analysis for long-term data is necessary for comprehensive understanding of the trend, the quality of customer service and costumer experience. In this paper, we propose a new IVR analysis model for large volumes of IVR data accumulated over a long period of time. The IVRCube proposed is an analysis model using online analytical processing (OLAP) on a multidimensional data cube that provides an easy and fast way to construct a multidimensional IVR analysis system for comprehensive and detailed evaluation of long-term data. The feasibility and applicability are validated, as the proposed IVRCube analysis model is implemented and applied to Academic Services costumer contact and ticketing IVR data.A Private Branch eXchange (PBX) é uma ferramenta indispensável no mundo dos negócios. As centrais telefónicas permitem que os funcionários realizem chamadas internas entre telefones, ou façam chamadas para a rede externa, também conhecida como Public Switched Telephone Network (PSTN). Com o aumento sistemático da utilização da Internet, há um interesse acrescido em entender quais os serviços que são oferecidos nas redes baseadas em Internet Protocol (IP). Um destes serviços é o Voice over IP (VoIP). O Enterprise Courier é um software IP PBX comercial para VoIP baseado na aplicação de código aberto Asterisk, que opera sobre Linux. O IP PBX Enterprise Courier suporta vários protocolos e serviços, por exemplo o Interactive Voice Response (IVR). O Cisco Unified Communications Manager (CUCM) também chamado de CallManager, é um sistema de processamento de chamadas IP, ou IP PBX, desenvolvido pela Cisco Systems. O CUCM permite fazer a gestão e operação de todos os componentes ativos de voz, incluindo telefones, gateways, equipamentos de conferência entre outros. Estes sistemas coexistem na rede de gestão de comunicações de voz da Universidade da Beira Interior (UBI), sendo que o sistema automatizado utilizado para o encaminhamento de chamadas dos Serviços Académicos na UBI utiliza a tecnologia IVR. Este serviço da UBI é uma das formas que os clientes da Universidade (alunos e não alunos) têm para obter informações e resolver questões de forma rápida e simples usando o telefone. Por ser um importante ponto de interface entre a universidade e a comunidade, a monitorização e análise de desempenho do IVR são essenciais para o funcionamento eficaz e gestão de recursos humanos atribuídos a este serviço, o que torna a tarefa de extrair os dados do sistema de VoIP e apresentá-los de forma a poder extrair deles informação útil à gestão, o centro deste trabalho de investigação. Para a análise dos dados, foi usada uma técnica de análise multidimensional de dados a longo prazo, necessária para uma compreensão abrangente da evolução e qualidade de serviço prestada ao cliente tendo como objetivo a melhor experiência possível por parte do cliente. Neste trabalho, propomos um novo modelo de análise de IVR para grandes volumes de dados acumulados ao longo de um extenso período de tempo. O IVRCube é um modelo de análise utilizando online analytical processing (OLAP) num cubo de dados multidimensional que fornece uma forma fácil e rápida de construir um sistema de análise multidimensional para avaliação exaustiva e pormenorizada dos dados ao longo do tempo. A viabilidade e aplicabilidade deste modelo são validadas, uma vez que o modelo de análise IVRCube proposto é implementado e aplicado ao serviço de contacto telefónico (IVR) dos Serviços Académicos da UBI

Quality assessment and usage behavior of a mobile voice-over-IP service

Voice-over-IP (VoIP) services offer users a cheap alternative to the traditional mobile operators to make voice calls. Due to the increased capabilities and connectivity of mobile devices, these VoIP services are becoming increasingly popular on the mobile platform. Understanding the user's usage behavior and quality assessment of the VoIP service plays a key role in optimizing the Quality of Experience (QoE) and making the service to succeed or to fail. By analyzing the usage and quality assessments of a commercial VoIP service, this paper identifies device characteristics, context parameters, and user aspects that influence the usage behavior and experience during VoIP calls. Whereas multimedia services are traditionally evaluated by monitoring usage and quality for a limited number of test subjects and during a limited evaluation period, this study analyzes the service usage and quality assessments of more than thousand users over a period of 120 days. This allows to analyze evolutions in the usage behavior and perceived quality over time, which has not been done up to now for a widely-used, mobile, multimedia service. The results show a significant evolution over time of the number of calls, the call duration, and the quality assessment. The time of the call, the used network, and handovers during the call showed to have a significant influence on the users' quality assessments

IP-based NGNs and Interconnection: The Debate in Europe

Historically, interconnection in the world of the Internet has been approached significantly differently from interconnection in the fixed Public Switched Telephone Network (PSTN) and the mobile Public Land Mobile Network (PLMN). As fixed and mobile networks evolve to Next Generation Networks (NGNs) based on the Internet Protocol (IP), it becomes increasingly necessary to merge these perspectives in order to achieve a unified and integrated approach to network interconnection. There is a rich history of economic analysis of IP-based and of conventional switched networks that began to converge early in this decade. In 2008, this issue is coming to a boil, as regulators seek to provide regulatory certainty for the build-out of NGNs, even in the face of substantial uncertainties, and even though practical experience with NGNs is still in a very preliminary state. What can we learn from the historical evolution of the theory of interconnection for Internet, NGN, PSTN and PLMN? What issues are "in play" today? What is the appropriate destination in the long term? What nearer term measures are appropriate?interconnection, NGN, Internet Protocol (IP), bill and keep, Calling Party's Network Pays (CPNP), peering, transit.