Google Duo offers a feature called Knock Knock which changes how your phone works when youre video calling someone.
Your video is then shown on the call screen before the recipient picks up or declines the call.
Tip: Knock Knock only works for users in your contacts, and doesnt work for strangers.
This reduces, although doesnt eliminate the risk of the system being abused.
Thankfully if you want to turn off the Knock Knock feature, it is easy to do so.
hit the cogwheel icon in the top-right corner to open Google Duos tweaks.
It will also prevent you from seeing the video of someone calling you before you pick up the call.
For Knock Knock to work, both parties need to have the feature enabled.
nudge the Knock Knock slider, found second from the top, to the Off position.
