Welcome to the Google Duo Help CenterGet started with Google DuoSet up Google DuoTips for using Google DuoFind and invite contactsHelp make Google Duo betterMake video calls from Google Allo with DuoMake a callStart a call with anyone, anywherePreview video calls with Knock KnockBlock numbers from calling you on Google DuoMake video calls with your Android Phone, Contacts, or Messages appSee your video call while using another appChange settingsLimit how much mobile data Google Duo usesSet phone to vibrate for callsDisconnect your phone number from Google DuoTroubleshoot issuesHow to send feedbackCan’t verify phone numberCan't find or sync contactsFix sound or video call problemsCall notifications aren't working