Duo Device Overview

 SDSU supports a range of devices, which are displayed below.

duo devices

Device Options

  • Smartphone: The most flexible and versatile option. Using a smartphone with the Duo Mobile app,  lets you MFA four different ways, as listed below:
    1. Duo Push - an automatic notification is sent to your phone
    2. Text Message (SMS) - passcodes are sent in a batch of ten, via SMS text
    3. Phone calls - your phone is automatically called
    4. Passcodes the app automatically generates a passcode
  • Landline: A telephone call to any landline phone will prompt approval or denial of the authentication attempt. A touch tone-enabled phone is eligible to be enrolled.
  • Cell Phone: Simple and convenient. Can be called as a phone or used as a text code (SMS) passcode generator.
  • Tablet: Enroll your tablet and receive Duo push notifications and passcodes to MFA through the Duo Mobile app.
  • Physical Token: A small lightweight keyfob that can be attached to your keychain. Pressing the button on the keyfob will generate a passcode for you to use with MFA. 

Device Recommendations

Deciding on which multi-factor authentication device is best for you is dependent on a variety of factors you must consider. Regardless of which method you choose, it is highly recommended that you enroll multiple devices, making it less likely you are locked out of your account.

DUO Mobile App

The Duo mobile app on your smartphone or tablet is the recommended option. Passcodes are generated easily within the app, even without service. If you have an Android phone, you can opt to have an email activation link sent to you instead of granting the application permission to use the camera for added privacy.


A token should only be used to authenticate if you do not have access to a mobile device or landline. Duo tokens are limited in quantity and provided upon request only to SDSU faculty, staff, and students. Duo tokens are distributed from the SDSU Library. As part COVID-19 protocols, contactless pickup will be provided for Duo tokens, which will be part of the Library's “Domeside Pickup” program.

For faculty and staff requesting a Duo token, create a ticket using the Service Portal. Please note in the ServiceNow ticket or assign to AA-LIB-Help Desk, if you are able to designate assignment groups. Pickup days and times are currently Monday through Thursday, 12:00 p.m. to 2:00 p.m. You will be asked to show your RedID. The SDSU Library Circulation Desk will send notification through the ServiceNow ticket providing information on when the token is ready for pickup. **If someone will be picking up a token on your behalf, please also note that in the ServiceNow ticket.**

For students requesting a Duo token, please contact the Library Computing Hub Help Desk by phone at 619-594-3189, email at [email protected], or chat at library.sdsu.edu/askhub

Lost or damaged tokens will be replaced at no charge. However, multiple incidents of lost or damaged tokens may revoke eligibility to receive replacement tokens.

General Duo support information is provided here.

Phone Calls and SMS Text Messages

Phone calls and SMS text messages are quick, easy, but not the most secure. SMS messages can be easily intercepted or redirected when traveling and can fail with bad reception. Authenticating through a landline is better, but not mobile friendly.