Template:DuoMobileSMS

SMS passcodes can be used as an alternate way to authenticate. Not all sites permit the use of SMS passcodes. Duo will only display the options allowed for authentication. You must have a SMS text capable device already registered with Duo to use this option. For authentication, choose the “Send text message passcode” option to receive a one time passcode via SMS text.

NOTE:  in Duo, a "Passcode" is numerical and is NOT the same as your password.