What is Multi-Factor Authentication?
When using Office 365 you have the option to enforce users to use multi-factor authentication, this is essentially making users provide contact details to help secure their accounts, users are required to acknowledge a phone call, text message, or an app notification on their phone after correctly entering their password. Only after this second authentication factor has been accepted can a user then sign in. However this can cause issues when they get a new phone numbers as the MFA prompts will continue to go to the phone which you used to set up multi-factor authentication. Unfortunately Microsoft do not give the option for you to simply change your MFA details users will need an administrator to log into the administrator centre to reset the details for them.
How is a Multi-Factor Authentication reset performed?
An administrator will need to log into the Office 365 admin centre and then go onto ‘active users’. They will then need to search for the user and click on the name that comes up (this will bring up a side panel with information about the user). If they them scroll to the bottom of this information panel there will be an option that says ‘manage multi-factor authentication’. This will open a new tab with all the users in your organisation that use Multi Factor Authentication, from here you can search for the user and if you left click on their name to the right hand side of the screen you will get the option to ‘manage user settings’ click then then you will be presented with three options. The administrator will need to select the first option which says ‘Require selected users to provide contact methods again’ once saved the next time the user tries to log into portal.office.com they will need to provide their selected contact methods again.