Using the NNS dapp to add a phone as a secondary device
To add a phone to your Internet Identity, select “Add a new Android phone” when verifying your identity with ic0.app. You’ll then be prompted to scan a code using a QR scanner app on your phone. Once scanned, on your phone screen, you’ll be asked if you want to “connect with QR code.” Make sure to have the option, “Remember this computer,” selected and continue by tapping “Allow.”
Your phone will begin connecting on the next screen. Allow Chrome to “find, connect to, and determine the relative positions of nearby devices.”
Then try verifying your identity by selecting your registered phone, which should now be listed as an option. Check your phone to accept a notification to “verify with his phone.” Then enter in the characters on your computer screen to confirm your phone as a new device.
Verify to complete the registration process and log in.
For more information on how to create an Internet Identity, visit the Internet Computer Wiki.