MFA & Verification Issues

How to Change Phone Number for Microsoft 365 Two-Factor Authentication

Maira Mehtab Sep 21, 2026 869 views

Question details

The user needs to update the phone number associated with their Microsoft 365 two-factor authentication (MFA) because they no longer have access to the old number.

Product: Microsoft 365
Device & OS: not provided
Scenario: Attempting to log into a school or institution-managed Microsoft 365 account but unable to pass the MFA prompt due to a changed phone number.
Observed behavior: The login process is blocked at the two-factor verification stage because the verification code is being sent to an inaccessible, outdated phone number.

Before you start

Check if you previously set up an alternative authentication method (like an authenticator app or a secondary email) before attempting to change your security info.

Solution 1Recommended

Use an Alternate Authentication Method

If you have a secondary authentication method configured, you can bypass the SMS prompt to access your account and update your phone number.

This method is only applicable if you have already set up the Microsoft Authenticator app, a hardware token, or an alternate email address alongside your old phone number.

Sign in with an alternate method

Go to the Microsoft 365 login page. When prompted for two-factor verification, click 'Sign in another way' and select your alternative authentication method.

Access My Sign-Ins

Once logged in, navigate to the 'My Sign-Ins' portal or your account's 'Security info' settings page.

Update your phone number

Locate your old phone number in the list of authentication methods, click 'Change' or 'Delete', and follow the prompts to add and verify your new phone number.

Solution 2

Contact the Institution's Microsoft 365 Administrator

If you do not have an alternate verification method, your IT administrator must reset your MFA settings.

Solution 3

Contact Microsoft Data Protection Support (For Admins Only)

If you are the sole administrator for the Microsoft 365 tenant and are locked out, you must contact Microsoft Support directly.

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Frequently Asked Questions

Why can't Microsoft Community Support reset my two-factor authentication?

For strict privacy and security reasons, Microsoft community agents and forum moderators do not have backend access to view or modify user account details, including MFA settings. Only your organization's IT administrator has the authority to change these settings.

What is the 'My Sign-Ins' page?

The 'My Sign-Ins' page is a dedicated security portal provided by Microsoft where users can manage their active login sessions, review recent sign-in activity, and update their security information, including passwords and MFA methods.

How long does an MFA reset take when done by an IT administrator?

Once the IT administrator initiates the reset in the Microsoft Entra admin center (formerly Azure AD), the change is usually instantaneous. You will immediately be prompted to set up a new verification method upon your next login attempt.

Can I use an authenticator app instead of a phone number for Microsoft 365?

Yes, Microsoft highly recommends using the Microsoft Authenticator app (or another compatible TOTP app) as it is generally more secure and reliable than receiving SMS text messages, especially if you travel frequently or change phone numbers.

Login & Account Issues