Duo cannot be installed on some smartphones. To determine if your phone might need to be updated, check Duo's documentation:
iOS support
Android support
If your phone does not support Duo (which means you can't use the Duo mobile app when you log into Bucknell's systems), you can still get SMS text messages to authenticate, but there are limits with that system. If you have questions about authenticating with Duo when your smartphone no longer is supported, please contact the Tech Desk.