How to Setup Alternative Authentication Method for Microsoft 365

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This article provides step-by-step instructions for configuring an alternative phone number for SMS-based multi-factor authentication (MFA) in Microsoft 365. Setting up a backup authentication method ensures you can maintain access to your account even if your primary device is unavailable.

User Self-Service Setup

Step 1: Access Security Settings

1. Navigate to https://mysignins.microsoft.com/security-info
2. Sign in with your Microsoft 365 credentials
3. If prompted, complete authentication with your current method

Step 2: Add Alternative Phone Number

1. Click the “+ Add method” button
2. From the pop-up window, choose the “Phone” or “Alternate phone” option
3. Choose the correct “County Code“, then enter the phone number.

You can only have one phone number associated with your account to receive the MFA code via SMS. If you only have ‘Call‘ as the verification method, please check the existing methods.

Step 3: Configure SMS Settings

1. Select “Text me a code” as the preferred method
2. Click “Next”

Step 4: Verification

1. You will receive a 6-digit code via SMS to the alternative number
2. Enter the code in the verification field
3. Click “Next” to complete setup

Consider Other Alternatives

We also high recommand that you explore other phishing-resistant authentication methods we offer, such as:

• Passkey (FIDO2)
• Passkey in Microsoft Authenticator
• Windows Hello for Business
• Certificate-based authentication

Escalation Path:

Please get in touch with [email protected] if you encounter any issues.