Assume that you join a conference by using Microsoft Lync 2010, and then you transfer audio to a Public Switched Telephone Network (PSTN) telephone. In this situation, the Start Recording command in the conference window is still available. When you click the Start Recording command, all activities except Audio Conferencing that are specific to making a recording are added to the recording. The activities that are added include Instant Messaging, Application Sharing, and Content Sharing.
Note: Because the audio part of the conference is transferred away from Lync 2010 to a PSTN phone, audio can no longer be recorded by Lync 2010.
To resolve this issue, install the following cumulative update:
2496325 Description of the cumulative update package for Lync 2010: April 2011
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
After you install the update package that is mentioned in this article, the Start Recording command is unavailable in the situation that is described in the “Symptoms” section.