Same issue here and it's VERY frustrating. I have spent countless hours troubleshooting this issue and speaking with support. I was told by support that ANY headset that is compatible with the computer is compatible with the softphone. Ironically, the support engineer I spoke with today told me that his headset doesn't even work with the app. The volume and mute buttons work, but not the answer button. We use Poly Voyagers, when I push the button to answer the call, I even hear the announcement "answering call" so it must be something with the app.
A twist:
I was able to get the buttons to work on 2 devices. I turned off Windows Bluetooth, and connected Bluetooth the dongle that came with the headset. The answer button works most of the time. Using the same method on our other devices, I cannot get the buttons to work. Please escalate this issue to engineering.
