Good reading when looking into QoE.

With the introduction of voice capabilities in Microsoft® Office Communications Server 2007, greater attention than before is required to ensure that the end user voice experience matches or exceeds traditional time-division multiplexing (TDM) desk phones. Microsoft’s approach, called quality of experience (QoE), is built on the premise that the end user’s perception of the quality of the conversation is the best measurement…

http://download.microsoft.com/download/C/B/2/CB26ABCE-3C65-4965-855C-38BE33D22BAC/Quality of Experience A Practical Approach to Deploying Real-Time Communications.doc