Duo is a one-to-one video calling app for everyone – designed to be simple, reliable and fun so you never miss a moment. Features: Simple interface Call any of your contacts with just one tap, with a simple interface that brings video to the forefront. High quality video Experience faster and more reliable video calls, whether you’re on Wi-Fi or on the go. Cross-platform Video call all your friends on smartphones with just one simple app. Audio Calls Make audio-only calls to your friends when you can’t have a video call. *Data charges may apply. Check your carrier for details.