261 Copyright © 2015, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 16 DOI: 10.4018/978-1-4666-7377-9.ch016 Quality Analysis of VoIP in Real-Time Interactive Systems over Lossy Networks ABSTRACT Voice over Internet Protocol (VoIP) systems have been spreading massively during the recent years. However, many challenges are still facing this technology among which is the lossy behavior and the uncontrolled network impairments of the Internet. In this chapter, the authors design and implement a VoIP test-bed utilizing the Adobe Real-Time Media Flow Protocol (RTMFP) that can be used for many voice interactive applications. The test-bed was used to study the efect of changing some voice param- eters, mainly the encoding rate and the number of frames per packet as function of the network packet loss. Several experiments were conducted on several voice fles over diferent packet losses, concluding in the best combination of parameters in low, moderate, and high packet loss conditions to improve the performance of voice packets measured by the Perceptual Evaluation of Speech Quality (PESQ) values. INTRODUCTION The market penetration of VoIP has massively influenced traditional telephony as witnessed by the popularity of many VoIP services and applica- tions (e.g. SKYPE, Cisco TelePresence, Ekiga and Oovoo (Vaughan, 2012)). It has become one of the most popular Internet Protocol (IP) based real- time communication services in recent years, it is of no doubt that VoIP networks are cost-effective over conventional telephone networks with Time Division Multiplexing (TDM) and leased lines. In real-time interactive systems, VoIP has been entitled an important role in enabling voice based real-time services, such as voice conferencing, that is applied in various sectors and fields every day. According to Zhao & Yagi & Nakajima & Juzoji, (2002). VoIP is taking a firm hold in the telecom- munication market for a wide range of interactive applications including telemedicine and e-health. Maha Z. Mouasher The University of Jordan, Jordan Ala’ F. Khalifeh German-Jordanian University, Jordan