Google Two Factor Verification options include three that you can use even if you don't have a mobile phone. This article explains how to set up those options, but you can view this Google article for more information.
Setting up Backup Codes
Backup codes are 10-digit numbers that you print out and keep with you in case you lose access to other 2nd steps. They can be useful when you do not have your cell phone. Each backup code can be used only once, however, you can get a new set of codes at any time.
For instructions on how to Create & View a set of backup codes, please visit support.google.com/accounts/answer/1187538
We recommend that you print out your codes, and then store them in a private but convenient location. You should consider carrying these backup codes in your wallet – when printed they are approximately the size of a business card.
Things to remember about backup codes:
If you need to use a backup code to sign in, click Try another way to sign in when signing in to your Google account
- Each backup code can only be used once.
- When you use a backup code, put a check in the adjacent box so that you know it has already been used.
- If you lose your backup codes you can view them by going to the 2-Step Verification page (see steps here) and clicking SHOW CODES in the Backup codes section.
- If you use all of your backup codes, you can generate a new set following the same procedures mentioned above (visit support.google.com/accounts/answer/1187538).
Setting up a Phone Call
An automated call can be sent to your desk phone or home phone with a verification code as a second factor. A 6-digit code may be sent to a number you’ve previously provided. Codes can be sent in a text message (SMS) or through a voice call, depending on the setting you chose. To verify it’s you, enter the code on the sign-in screen. Although any form of 2-Step Verification adds account security, verification codes sent by texts or calls can be vulnerable to phone number-based hacks. Never give your verification codes to anyone.
Setting up a Security Key
A security key is a piece of hardware that you can insert in a port on your device and then touch your fingerprint to when prompted for a second factor. These keys are a more secure second step. If you have other second steps set up, use your security key to sign in whenever possible. See more information at https://support.google.com/accounts/answer/6103523?hl=en
Setting Up Trusted Computer
No matter which option you use as your second factor, you can choose to trust the computer so that you aren't prompted for a second factor when you use that computer to log into your account in the future. It depends on the cookies in your browser's settings.
For instructions on how to add or remove trusted computers, please visit https://support.google.com/accounts/answer/2544838