Are you trying to use WebRTC (default), Flash or running Roll20 through Google Hangouts? Have you tried all three of the available voice/video options to see if one of them works? Can the other user hear you or is it silent for the both of you? If you're both using WebRTC, are you both using either the latest versions of Chrome or Firefox? Did you make sure that both you and the user has their settings set to "Voice" or "Video & Voice" under both "I want to Broadcast to others:" and "I want to Receive from others:"? Did you make sure your "Video/Player Avatar Size:" is NOT set to "Names Only"? Sarah, I'm convinced, is a thread ninja.