Security solutions in VoIP applications: State of the art and impact on quality

Among the multimedia services over IP networks, voice/telephone communications are gaining greater and greater interest, either for personal and business applications. As a consequence, security solutions to guarantee privacy of communications and users' authentication become a necessary feature. This paper examines the state-of-the-art of security solutions for Voice over IP applications: the actual availability and support of such security facilities, through open source clients and servers, are discussed and tested experimentally. Moreover, the impact of security mechanisms on the perceived quality of the voice communications is evaluated, by means of suited software tools, that allow to simulate different traffic conditions and bandwidth availability, and to compare the corresponding audio mean opinion score values obtained.