As much as this might be trivial to some, there are some people out there that aren’t aware on how to get to the voice calls in Google Duo’s. The Duo app doesn’t clearly indicate on how to get there.
Here’s a short little video that illustrates that from the top underneath the navigation bar just swipe down to see the toggle between voice and video.
[embedyt] https://www.youtube.com/watch?v=0lShSczidNw[/embedyt]