I have modified the sample.html (and accompanying sample.js) files in a way that may be helpful to those who want to learn more about Jabber SDK Voice/Video. I added a log window to the page where you can see information about events that occur when you place calls, hold calls, mute audio, etc.
Simply download the attached files. Place sampleWithObserver.html in the same directory as sample.html. Put sampleWithObserver.js in the js directory below that, the same place where you'll find sample.js.