MFA & Verification Issues

How to Change a Work Account Phone Number in Microsoft Authenticator

Bushra Parveen Oct 10, 2026 869 views

Question details

Users need to update or change the phone number used for multifactor authentication on their Microsoft work account, especially after losing access to the original phone number.

How to Change a Work Account Phone Number in Microsoft Authenticator

Product: Microsoft Authenticator
Device & OS: not provided
Scenario: A user no longer has access to the phone number currently registered for their work account's Microsoft Authenticator setup and needs to replace it with a new number.
Observed behavior: The user is unable to log in or update their security settings independently because the system sends verification codes to the inaccessible old phone number.

Before you start

Verify whether you are an end-user or an IT administrator, as changing a lost work account phone number requires administrative privileges within your organization's Microsoft Entra environment.

Solution 1Recommended

Reset MFA Methods via Microsoft Entra Admin Center (For Administrators)

IT or Authentication Administrators must use the Microsoft Entra admin center to clear the user's old phone number and trigger a new setup prompt.

When an employee loses access to their primary authentication phone number, self-service password reset and MFA updates are typically locked out for security reasons. Administrators must revoke the existing sessions and force a re-registration.

If you encounter persistent errors during this process, you may need to escalate the issue by contacting Microsoft Support directly.

Log in to Microsoft Entra

Open your web browser, navigate to the Microsoft Entra admin center, and sign in using an account with Authentication Administrator privileges.

Locate the User Account

From the left-hand navigation pane, select 'Users', and then click on 'All users'. Use the search bar to find and select the specific user account that requires the phone number update.

Access Authentication Methods

On the user's profile page, locate the left sidebar and click on 'Authentication methods'.

Revoke and Re-register MFA

Click on 'Revoke multifactor authentication' to disconnect the old phone number and sessions. Next, click 'Require re-register multifactor authentication'. This forces the user to set up their new phone number and Microsoft Authenticator app the next time they sign in.

Reset MFA Methods via Microsoft Entra Admin Center (For Administrators)

Setup Complete: Once the administrator completes these steps, the user can log in with their password and follow the on-screen prompts to register their new phone number.

Solution 2

Request an MFA Reset from IT Support (For End Users)

If you are an employee who has lost access to your work phone number, you cannot change the number yourself. You must contact your IT department to regain access.

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Frequently Asked Questions

Why can't I change my work account phone number myself in Microsoft Authenticator?

For security reasons, organizations restrict self-service security changes if you cannot authenticate with your existing methods. If you lose access to the primary phone number, an IT administrator must verify your identity manually and reset the MFA settings to prevent unauthorized access.

What should I do if my administrator cannot complete the MFA re-registration?

If the administrator encounters errors or is unable to complete the 'Revoke and Re-register' steps in the Microsoft Entra admin center, they will need to escalate the issue by contacting Microsoft Support directly for backend assistance.

How can I prevent getting locked out of Microsoft Authenticator in the future?

Once your administrator restores your access, navigate to your account's 'Security info' page and set up multiple verification methods. Adding a backup phone number, a secondary email address, or configuring the Authenticator app on a secondary device ensures you have alternate ways to log in.

Login & Account Issues