Issue: How can I continue the login process if my phone doesn't have access to the internet right now?
Environment: smartphone, smart phone, mobile phone, mobile device, tablet, Duo Mobile app/application, no internet connection
Resolution: 1) Use another previously-enrolled device or 2) use the Duo app to get a temporary passcode that you can use.
A key to avoiding possible problems is to have a previously-enrolled backup device. If your primary device is a phone, a secondary device could be a tablet or fob - whatever you would have with you when you want to authenticate. Another key to avoid being stuck is to know that the Duo Mobile app has the ability to generate a passcode even without an internet connection.