Some applications that work outside a browser are not yet compatible with two-step verification and can not ask for verification codes, such as:
- Older Android smartphones
- Google Voice mobile app for the iPhone
- Chrome Sync
- E-mail clients such as Microsoft Outlook
- Chat clients such as Google Talk, AIM, etc.
To use these applications, you must first generate an application-specific password. Then you must specify that password in the password field of your application instead of your regular password. You can create a new application-specific password for each application that needs one.
To do so, go to: https://accounts.google.com/IssuedAuthSubTokens and scroll all the way down.