Using Google Voice on the Computer

I have a Google Voice Account with a Google Phone Number.  When I am signed into Google Voice (https://www.google.com/voice), there is the call button (feature).  I hit that button and enter the phone number - choosing Google Voice.  

I can "hear" my computer ringing, but there is nothing on my screen / browser for me to "answer".   I have tried Firefox and Chrome, but I don't see anything prompting me to answer.

The only way I can successfully call is to click on http://www.google.com/chat/voice/ and that takes me to my GMail account with the dialer in the lower right hand corner of the browser.  But once I close that box, I have to go back to this link.  

How do I "answer" my computer to make a call?

Thanks!