As an alternative to the SMS entry, this option allows users to authenticate themselves using a smartphone app like Authy or Google Authenticator.
Setting up the smartphone authentication:
Download a QR code scanner such as Authy/ Google Authenticator
On the log in page, click the 'Send Code' button. Key in the code received via SMS and click 'Verify' button.
Scan the QR code provided to generate a 6 digit token.
Enter the token, and click 'Verify' button to log in.
For subsequent logins, you won't need to scan the QR code. You will use the authenticator app installed to generate tokens.
In case you need to re-install the app just click on the highlighted bit and follow the above steps.