Google is making its own version of FaceTime for Android and iPhone
It's not yet available, but Google promises it's coming soon for both Android and iPhone.
Select a contact or phone number, call them, and start a video conversation. It's simple.
Google is positioning its expertise at web video calling, drawn from Google Hangouts and the Chrome browser, as something that sets Duo apart.
Obviously, it's not groundbreaking. But unlike Apple FaceTime, Duo works across both Google Android and Apple iPhone and iPad.
That gives it a much broader potential customer base - and a wider range of people you can call. That could be enough to give Apple pause.
Duo was Google's second messaging app announcement of the day, after smart chat app Allo.