A variety of options exist to accommodate users without smartphones: -An ordinary mobile phone (not a smartphone), or even a traditional desktop phone, can be used to authenticate with Duo. -If the user doesn't have any phone, the institution can elect to purchase a traditional hard cryptographic one-time password token for that user at $20/token, or the school may want to consider an inexpensive prepaid basic cell phone for this purpose. -Finally, if the person without a phone is just a regular user (i.e., not a user with special privileges or access to sensitive data), yet another option would be to selectively disable the use of Duo for that user.