So if you want to make a video call to any of your friend on Duo and they have not installed the app. The update has brought an updated look to the contact list on Duo and a fun rearrangement of pixels as well. Recipients can answer the call by dragging up on the phone icon, mute their mic or change cameras, and hang up just like a regular Duo call. Until now, one of the major requirements for it other than a working internet connection (obviously!) is to be using the same app or software to make the call.
As reported by Android Police, the latest update in Duo includes this attribute to call users, with the spontaneity of an "Instant App" like experience called App Preview Messaging that's sported by Google Play services that allow Android users to receive calls through Duo. If the user navigates away from the call while still connected, there is a persistent button that will put the Duo caller back into view.
Another comment on the thread noted that Google Duo compatibility is now part of the stock Android Dialer and allows calls to non-Duo users. It's exactly how the Duo works but without it running on their smartphone. But it is not going to work with everyone on your contacts as the report shows that only some legitimate contacts are being listed.
Obviously Google would prefer it if every Android user chose to roll with Duo for their video messaging needs. The option to install Duo pops up after the call has ended, and so does the option to block the caller from calling ever again. But, most of the Google messaging apps are caught up in a hitch at this stage, pushing few users towards either Allo or Duo.
It's clever way for Google push its app.
Google said it'd make App Preview Messaging available to all developers after an initial preview program, but that's yet to happen.