Secure and efficient: Google says Duo calls are end-to-end encrypted. Once you're in a call, you can mute your mic, swap between front and back cameras to change what your caller sees, tap your image in the bottom-left corner to make it swap places with your caller's image, and choose whether to use an internal or external mic. You also see recently called friends in the app's main window. If you want to call someone who doesn't yet have the app, find them in your friends list and click Invite to send them a link to the app. Make a call: When you click the Video call button, you see a list of friends who are running the app. Likewise, anyone with your number can contact you if you are both using the app. Uses your phone number: The app is based on your phone number and lets you call anyone in your contacts list who is also using Duo. Duo's interface is easy to navigate: Tap the Video call button to ring someone up, and tap to accept a call from a friend. ProsĮasy to set up and use: After you download Google Duo, verify your phone number and approve a few permission requests, and then you're good to go. Duo by Google lets you make simple person-to-person video calls, across Android and iOS.