Switch from front to back camera during a video call

On Microsoft Surface Pro:

Wire will select the facing default camera to display videos when video calling. To switch from front to back camera and vice versa to make video calls:

1. Select the Windows camera app.
2. Switch the cameras.
3. Return to Wire and start a video call.

Learn more here: Microsoft Windows Surface Pro Tutorial 

On mobile devices:

While on a video call: Tap  underneath the self preview to switch to the back camera. Tap it again to switch back to the front camera.