Duo, a video calling app announced at Google I/O 2016, released today in the App Store as a free download. A one-to-one video calling app “for everyone,” Duo allows iPhone users to call their Android-toting friends, and vice versa. After signing up with your mobile phone number, you can place video calls to contacts who also have Duo installed on their device. According to Google, Duo for Android and iOS began rolling out today and will be live worldwide in the next few days.
Duo includes a feature, called Knock Knock, which lets you see live video of your caller before you answer, giving you a sense of what they’re up to and why they want to chat.
Once the call is accepted, the video continues uninterrupted.
Google claims Knock Knock helps make the video calling experience “more spontaneous and welcoming, helping you connect with the person before you even pick up.” The company, however, did not specify whether Knock Knock is available on iOS and in which form given iOS does not permit video to be shown before the user unlocks the handset and answers the call.
Duo’s minimalist user interface strives to take the complexity out of video calling and the underlying technology was designed to connect video calls quickly and work well even on slower networks by adjusting quality to changing network conditions.
When bandwidth is limited, Duo will “gracefully reduce the resolution” and/or switch between Wi-Fi and cellular data automatically, without dropping the call.
“We built Duo with an emphasis on privacy and security, and all Duo calls are end-to-end encrypted,” says the company. As mentioned, no separate account is required to use Duo—all you need to sign up is your mobile phone number.