Could Skype be More Satisfying?

The phenomenal growth of Skype in recent years has surpassed all expectations. Much of the application’s success is attributed to its FEC mechanism, which adds redundancy to the voice streams to sustain audio quality under network impairments. Adopting the quality-of-experience (QoE) approach, i.e., measuring the Mean Opinion Scores (MOS), we examine how much redundancy Skype adds to its voice streams and systematically explore the optimal level of redundancy for different network and codec settings. This study reveals (1) Skype’s FEC mechanism, not so surprisingly, falls in the ballpark, but (2) there is surprisingly a significant margin for improvement to ensure consistent user satisfaction.