Google has quietly updated Duo to allow users to call people who don't even have the Duo app installed. This means that Google Duo users can make voice calls or video calls to their contacts using Duo even if the other person has never even heard of this particular messaging app.

The number of messaging apps Google offers has been well documented. There's Allo and Duo (which can now make voice calls) and Hangouts (which has been split into Chat and Meet). And all of them do pretty much the same thing. However, Duo does have a cool new trick up its sleeve.

No Duo, No Problemo

As first spotted by Android Police, Google Duo now lets you call people who don't yet have the app installed. This is made possible thanks to Google's App Preview Messaging feature, which lets certain apps to be used to contact other people without them needing to have the app installed.

There are some caveats to bear in mind. App Preview Messaging is obviously only available on Android, so you can't call your iOS-using friends. You will also only be able to call contacts who have added a phone number to their Google account, and switched App Preview Messaging on.

For those who don't have Duo installed, an incoming Google Duo call looks exactly as it would if you had Duo installed. The call will fill your screen, and you'll see the camera of the person calling you. You can then choose to answer the call, hang up, mute your mic, or change cameras.

It's at the end of the call that things get interesting. You'll be prompted to install Google Duo, or, if you feel aggrieved at the caller for calling, you can block them to stop it happening again. Either way, you'll have been given a taste of Duo without ever installing the app.

Google Promotes Duo

While App Preview Messaging isn't a new thing, it's not yet available to all developers. Which affords Google the opportunity to use the feature to push Duo onto more people. After all, what better way to promote your messaging app than allowing people to use it without installing it.

Are you a Google Duo user? If so, what made you choose Duo over all of the other messaging apps available? Do you welcome this change allowing you to call people who don't use Duo? Do you think it will help make Duo become more popular? Please let us know in the comments below!