MFA-Duo - What to do when changing SIM card, Phone Number or Phone

This document explains what you'll need to do if you've changed your SIM card, phone number or phone. The content of this document has be taken directly from Duo's support documentation and slightly modified to meet UW-Madison's implementation.

Changing SIM Card

Changing your SIM card will not affect the way you authenticate (even if it changes your phone number) because the Duo Mobile app is tied to your smartphone's hardware security module (HSM). You should still be able to accept a push or generate a passcode from the Duo Mobile app (even when your smartphone is in airplane mode or lacks cell/ wi-fi service). To generate a passcode:

  • Simply open the Duo Mobile app and click the UW Madison NetID Login down arrow located at the upper right-hand corner of your smartphone. This will generate a six-digit temporary passcode.
  • Enter the six-digit code provided on your smartphone in the Multi-Factor Authentication portal to complete the authentication process.

Permanently Changing Phone Number

Assuming the user still has Duo Mobile installed and the ability to authenticate via push or a passcode, they should follow the procedure for adding a new device. See MFA-Duo - Adding Secondary/Backup Devices

If they do not have any means of authenticating they should contact their help desk. We recommend deleting the old device as soon as possible, see MFA-Duo - Removing Devices

Changing Phone

Note: If you do not have access to your previously registered phone, you will need to get a temporary code to be able to access the Multi-Factor Authentication Portal in order to add your new phone. See MFA-Duo - Request a Temporary Passcode

Since Duo Mobile is tied to a specific device's HSM, the user will need to reinstall and reactivate Duo Mobile on their new phone. See MFA-Duo - First Time Setup for Smartphone or Tablet

Changing Phone, Keeping same phone number

In this scenario, you will simply need to reactivate Duo Mobile for your new phone by visiting

  1. Login with your NetID and password.

  2. Click Manage MFA Preferences and Devices.

  3. You will be prompted for MFA. If you do not have access to your previously registered phone, you will need to get a temporary code to be able to access the Multi-Factor Authentication Portal. See MFA-Duo - Request a Temporary Passcode

  4. Click the Device Options button next to your previously registered phone.

  5. Click Reactivate Duo Mobile.

  6. Install Duo Mobile on your new phone.

  7. Click I have Duo Mobile Installed.

  8. Follow the onscreen prompts to scan the QR code.

  9. Your phone should now be reactivated and ready for use with MFA Duo.

See accessibility & usability information

We work with our users to address access and usability barriers in the MFA user experience. Learn details about known access barriers and workarounds at MFA-Duo - Accessibility & Usability Information. If you encounter a barrier or need assistance, please contact the DoIT Help Desk or call (608) 264-4357.

For questions regarding how to get access to the MFA mobile app contact the DoIT Help Desk at (608) 264-4357 or email

How to get access to a Security Key or Duo Token/Fob 


Students, to obtain a token/fob, please contact the DoIT Help Desk (608) 264-4357 or email Students with disabilities can also request a token or security key at the McBurney Disability Resource Center, 702 W. Johnson St., Suite #2104, Madison WI 53715 on the 2nd floor.

Faculty, Staff, and Researchers

Employees can get access to devices for MFA at their Human Resources Office or IT department. For questions contact the DoIT Help Desk at (608) 264-4357 or email 

KeywordsNew phone change replace mobile smartphone smart device   Doc ID87477
OwnerMST SupportGroupIdentity and Access Management
Created2018-11-02 09:17:48Updated2022-05-25 15:15:35
SitesDoIT Help Desk, Identity and Access Management
Feedback  9   23