Google has launched a new bare-bones video-calling app, Duo, which will be available on iOS and Android, and enables users to enter into one-to-one video calls using phone numbers.

The mobile-only service focuses on simplicity, with a streamlined setup process that ties directly to your phone number and existing contacts list, and a UI that strips out anything unnecessary that can be carried out by Googles other apps. The one innovation is a feature called Knock Knock, that begins the video stream before calls are answered, so the user on the other end can see who is calling them.

“Video calling is the next best thing to being with someone in person, but too often it can be a frustrating or complicated experience,” said Justin Uberti, principal software engineer for Google Duo. “You shouldnt have to worry about whether your call will connect, or if your friend is using the same type of device as you are. Its no wonder that nearly half of us never make video calls on mobile.”

While the spartan approach to video calling may win Duo some fans, industry experts are questioning whether Google launching another siloed app into its ecosystem of communication tools is the right answer to taking on giants like Apples FaceTime, Microsofts Skype and Facebooks Messenger.

In addition to the traditional SMS it offers on Android, Google also has Hangouts, Spaces, Google Chat and its upcoming Allo messaging product, all with different features and use cases. This scattered approach is unlikely to challenge established products like FaceTime that are strongly integrated into Apples ecosystem and also offer a full range of features such as group calls and text chat.

Duo may have an advantage in emerging markets though, thanks to a feature that automatically reduces the video resolution where bandwidth is limited, even automatically switching to a voice call where data is extremely limited.

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