Coinbase

Coinbase provides several options for generating 2-factor authentication (2FA) codes with various levels of setup. 
 

Security key

Security keys are the most secure method for 2FA. For more information:

• Using/managing security keys
• Security Keys FAQ

TOTP

Google Authenticator, Duo, or similar authenticator apps provide a very secure configuration for 2FA. These do not require phone reception or internet access once set up. For more information on setting up: Managing Google Authenticator
 

SMS/Text

If you verify a phone number via text message without installing any Authy apps, you will automatically receive 2FA codes via SMS text message.

Note: If you have any Authy apps installed or Authenticator registered, you'll no longer be able to receive SMS codes. Please refer to 2-Factor Authentication Troubleshooting if you have lost your Authenticator or Authy app.

Landlines/Voice Call
It is not possible to receive 2FA codes delivered to a landline phone number by voice call. For security purposes, Coinbase does not support the delivery of 2-factor authentication (2FA) codes via voice call. If you have a landline registered with your Coinbase account, follow these steps to upgrade your security:

1. Sign in to the Coinbase website with your username and password
2. Click on the link "Unable to submit one-time code?" 
3. Click on "I no longer own the phone number ending in +1 xxx xxx 1234" (as an example)
4. Complete the Account Recovery process by following the steps listed
5. Increase your security by enabling Authenticator: https://www.coinbase.com/security_upgrade