I know someone whose 2-factor phone authentication was hacked... 
I use the Google Authenticator app, which makes the token only available to that specific device, rather than through SMS. This gets around the problem of cloning a phone number.iOS: http://itunes.apple.com/us/app/google-authenticator/id388497...Android: https://play.google.com/store/apps/details?id=com.google.and...