Instead of using verification codes, you can insert a Security Key into your computer's USB port for even more protection against phishing.
Best for those who:
serve in sensitive areas
don't have a smart phone
are comfortable carrying small hardware with them
aren't comfortable carrying paper with them
The Authy app for your computer or smartphone can generate verification codes. It even works when your device has no phone or data connectivity.
Relies on your phone having the same time as the computer you're logging in on.
Best for those who:
always have their smartphone with them
aren't comfortable carrying paper with them
You can print or download one-time use backup codes for times when your phones are unavailable, such as when you travel.
Best for those who:
don't have a smartphone or don't always have their smartphone with them
are comfortable carrying paper