• by Laurie Sullivan , Staff Writer @lauriesullivan, August 16, 2016

Google has finally released Duo, the video calling app for phones running iOS and Android operating systems, taking on Apple FaceTime. But will the images and audio from the app become another data point that Google will use to target advertisements?

The Alphabet subsidiary announced the one-on-one phone chat app during its I/O developer conference earlier this year. It works similar to Apple's Facetime, but scaled down.

The app focuses on one feature — video calling — and one unusual feature: the ability to see the caller before the phone connects.

The "knock-knock" feature allows the person receiving the call on Duo to preview incoming video calls from anyone in their content list, which means seeing the caller before they answer the phone.

In May, when Google announced the app at its 2016 I/O event, the company said the app will use the phone number as an identifier and the camera to display the video image prior to connecting the call.

Video calls connect quickly and work well even on slower networks, and the call quality adjusts to changing network conditions to keep users connected when bandwidth is limited, according to Google.

Google records every voice search that someone makes and keeps a running record of every search in its apps like Maps, YouTube, and Search. The Voice and Audio Activity page under the Activity controls in the My Activity section serves up every voice search ever made, so it makes sense that the company will also add a section for video calls.

Mine is paused when turned on, Google says the voice and audio activity feature, "Okay Google," helps to recognize your voice and improve search recognition by storing your voice and audio inputs into your account.