MFA & Verification Issues

How to Fix Microsoft 365 Business Sign Up Issues with a Vietnamese Phone Number

Maira Mehtab Sep 22, 2026 869 views

Question details

Users are experiencing verification failures when trying to sign up for Microsoft 365 Business using a Vietnamese mobile phone number.

Product: Microsoft 365 Business
Device & OS: not provided
Scenario: Creating a new Microsoft 365 Business account and attempting to complete the mandatory phone verification step.
Observed behavior: The phone verification process fails to accept the Vietnamese number or fails to deliver the verification SMS, preventing account registration.

Before you start

Make sure your mobile carrier allows international SMS messages, as Microsoft verification codes are often routed through international telecom gateways.

Solution 1Recommended

Correct Regional Settings and Phone Formatting

Selecting the proper region and formatting the phone number correctly usually resolves basic verification failures.

A common cause for verification failure is a mismatch between the selected region and the phone number's country code. Ensure you drop the leading zero from your local number when the +84 country code is applied.

Select the correct region

On the verification page, click the country dropdown menu and select 'Vietnam' to automatically apply the +84 prefix.

Enter your phone number

Type your mobile number in the input field, ensuring you omit the initial zero (for example, if your number is 098xxxxxxx, enter 98xxxxxxx).

Request code

Click 'Send code' and wait up to 60 seconds for the SMS message to arrive.

Formatting Note: Double-check that there are no spaces or special characters in the phone number field.

Solution 2

Use an Alternative Verification Method

Switch to email or authenticator app verification if phone-based MFA is blocked by your carrier.

Solution 3

Contact Microsoft Support for Security Restrictions

Reach out to Microsoft Support if the number is flagged by backend security restrictions.

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Frequently Asked Questions

Why is my +84 Vietnamese number not receiving the Microsoft verification code?

This usually happens due to mobile carrier blocks on international SMS, incorrect regional formatting during sign-up, or temporary Microsoft server delays.

Do I need to include the leading zero when entering a Vietnamese phone number in Microsoft 365?

No, when you select Vietnam (+84) from the country dropdown menu, you should drop the leading zero of your phone number for the system to process it correctly.

Can I sign up for Microsoft 365 Business without providing a phone number?

Microsoft typically requires a phone number for initial business account security verification. However, if phone verification fails, you may be presented with alternative options like the Microsoft Authenticator app.

Login & Account Issues