윈도우 365 계정 인증 시 오류 발생

Question

로그인시 2차 인증을 해야하는데

문자 인증은 "죄송합니다. 계정을 인증하는 동안 문제가 발생했습니다. 다시 시도해보세요" 가 나오는 상태로 세부정보상 Error Code: 399287

Request Id: 4bc49a52-79af-4164-80f6-404a3e473000

Correlation Id: b3e9b982-50ef-4579-bed1-2560791e58a6

Timestamp: 2025-09-04T01:45:13Z 이뜨는 상태입니다.

관리자 계정은 따로 존재하지 않고 해당 모든 부분으로 해결을 시도하려했으나 모두 로그인이 되어야만 할 수 있는 상태입니다. 빨리 응답 주시기 바랍니다.

계정 id 는 ********@teamplat.onmicrosoft.com 이며 빠른 확인좀 부탁드립니다..

Answer 1

Hello,
Thank you for posting on the Microsoft Q&A Support Forum

This error typically occurs when the phone number used for MFA has been flagged by Microsoft’s Phone Reputation service. That can happen due to Repeated failed login attempts, Suspicious activity from the number and Use of SMS in high-risk regions or networks. Hence when this happens, Microsoft blocks SMS verification for that number even if it’s legitimate. Here is what you can do:

Switch to Microsoft Authenticator App If you can still access the device where the account was signed in and Download Microsoft Authenticator on your phone Go to Settings > Accounts > Sign-in options > Security info Add the Authenticator app as a new method Set it as your default second factor This bypasses the SMS issue entirely.

If that does not work, since you can’t log in and there’s no admin, then you need to go to Microsoft 365 Admin Support Microsoft Office 지원에 문의 - Microsoft 지원 to open a ticket as they have the required tools to further support you on this issue.

Best Regards,

Odinaka | Microsoft Q&A Support Moderator