I just starting experiencing this same type issue myself.  I have a wireless Logitech H820e and when I make outgoing calls through FreshFone - I can hear the customer and they can hear me.  However, when I try to answer an INCOMING call, I can not hear the other end AT ALL...complete silence - but they are able to hear me.  I've checked all my sound settings and my phone works fine with GoToMeeting, Google Voice, Google Chat and outgoing FreshFone...but seriously need to figure out what's wrong with INCOMING calls soon.  

Nicholas,

Did you ever figure out a solution for why certain wireless headsets aren't working properly in FreshFone.  I have Logitech H820e and can make calls OUT of FF fine...but when customer calls in, they can hear me but I CAN NOT hear them.

I need to figure this out ASAP or I guess I need to return and buy different headset.  Thanks

For my situation I downloaded the  plantronics control panel and set the connection between the usb and headset to never loose connection. Also, I turned on auto sensing. This fixed the abilty to here, but the issue were having now is we would really like to push for using the headset button to answer calls. They need to  build this in there WebRTC. This would be beneficially to all user that way multiple headsets would work with freshfone. Hope that helps.