Duo is investigating issues where SMS/Phone Call authentications are not working when using Duo multi-factor authentication.
Any customers experiencing this issue should connect to a wi-fi network and switch to the recommended way of authenticating with Duo: using the Duo Mobile App. The app is free to install and only takes a few minutes to switch.
The instructions on switching from phone/SMS to the Duo Mobile App can be found here.
Thank you for your patience while the vendor works to restore this service. An update will be sent as more information becomes available.