If you set up 2-Step Verification, you can use the Google Authenticator app to receive codes even if you don’t have an Internet connection or mobile service.
Requirements
Note: If you have an account through your work, school, or other group, your organization might not allow 2-Step Verification. Check with your administrator to be sure.
To use Google Authenticator on your iPhone, iPod Touch, or iPad, you'll need:
- The latest operating system for your device
- 2-Step Verification turned on
- (optional to set up with QR code) iPhone 3G or later
Download the app
Set up the app
- On your iPhone or iPad, open the Gmail app
. Tap Menu
Settings
- At the top, tap Security.
- Under "Signing in to Google," tap 2-Step Verification.
- Under "Set up alternative second step," find "Authenticator app" and tap Set up.
- Follow the steps on the screen.
- To verify it's working, get a code from your Authenticator app. Enter it in your settings.
. Tap Menu 
Settings If your code is correct, you'll see a confirmation.
If your code is incorrect, try again. If you’re still having trouble, you might want to verify that the time on your device is correct or read about common issues.
Setting up 2-Step Verification for multiple Google Accounts
Google Authenticator can issue codes for multiple accounts from the same mobile device.
Each Google Account needs a different secret key. To set up additional accounts, turn on 2-Step Verification for each account and use the same Google Authenticator app.
Setting up Google Authenticator on multiple devices
You can set up Google Authenticator so that you can generate verification codes from more than one device.
- Make sure that you have Google Authenticator downloaded on all devices that you want to use.
- Go to the 2-Step Verification section of your Google Account.
- If you've already set up Google Authenticator for your account, delete that account from Authenticator.
- Follow the steps on the screen to set up 2-Step Verification for the Authenticator app. Use the same QR code or secret key on all your devices.
- To check if it's working, make sure the verification codes on each device are the same.
Google Authenticator does not generate App Passwords. After turning on 2-Step Verification, If you see a prompt for a new App Password, sign in using an App Password.