Users without Internet connectivity or smartphones can still authenticate easily with Duo’s SMS passcode method. After completing primary authentication, Duo will send you a one-time passcode via SMS, delivered to your phone.
Type the passcode into the authentication prompt on your screen and press enter to authenticate and access your account. Users can get new passcodes sent to their phones at any time.
The use of SMS passcodes is one of many two-factor authentication methods that Duo provides to support your diverse user base.