Google wants to change the way people video chat on mobile devices with the release of its new Duo app.
Duo, which is positioned to rival Apple's FaceTime, is available to iOS and Android users.
After downloading the app, all a user needs is a phone number to reach friends in their contacts list who have Duo.

People who prefer to screen their calls will enjoy "Knock Knock," one of Duo's differentiating features, that allows a user to see a video stream of the person calling you before they choose whether to answer.
From a technical standpoint, Google is touting a seamless video calling experience on the app, even if two friends use different operating systems.
Duo is also designed to adjust for changing network conditions, so when bandwidth is limited it will reduce the video resolution without the call becoming choppy. A user could also begin a call on Wi-Fi and walk out the door, switching to cellular data, without the quality of the call being impacted.
Google first revealed the existence of Duo at the company's annual developers conference in May. The app is available for download today and is expected to be released worldwide in the next few days.