With Office Communicator 2007 R2, you can add audio and video to an IM session without opening a new Conversation window.
What do you want to do?
Add audio to an IM session
During an instant message session, click the Call button or the View more options for calling this contact button next to the Call button.
Add video to an IM session
During an instant messaging session, click the Start a video call button.
Set up audio and video
Office Communicator 2007 R2 provides a Set Up Audio and Video option that you can run to make sure your devices are working correctly and that your speaker and microphone volumes are set correctly.
To start audio and video setup
In the Communicator window title bar, click the Menu button, point to Tools, and then click Set Up Audio and Video.