There are three ways that you can authenticate through Duo:
Duo Push (recommended)
If you enrolled a smartphone and are using the Duo Mobile App, you will receive a push notification requesting confirmation of your login. There are several ways of confirming your login from the lockscreen to the app itself. Pressing Approve will continue the login process. Pressing Deny will stop the login.
Method 1: From the Lock Screen
With your phone locked, swipe left or force touch the notification to approve or deny the log in.
Method 2: Incoming Notification
While your device is unlocked, tap the notification to be given the approve or deny options.
Method 3: Notification Center
If you miss the incoming notification you can still authenticate within the notification menu.
Swipe left to reveal the approve/deny options available and tap the one you want.
Method 4: Using the Duo Mobile App
When in the Duo App you will get a notification within the app itself for authentication.
Tap the green bar to approve or deny the request.
If you are in a location where you cannot receive either network or cellular service, you can generate a passcode on your mobile device by pressing the drop-down arrow. This will generate a 6 digit number that you can enter in the passcode box and allow you to log in.
If you select this option, you will receive a phone call asking you to confirm that you want to log in. Pressing any key on your keypad will approve your login. If you do not want to log in, all you have to do is hang up.