Microsoft 365 admin center - Unable to login by verifying using SMS

Question

Microsoft 365 admin center - Unable to login by verifying using SMS

Phill Hayman 210

e're unable to log into our Microsoft 365 tenant's Admin Center because verifying using SMS is not working. The system claims the account is not verified but doesn't allow any other options (error Code 399287).

I found in a few other post this can be solved by the engineering team so I'm tagging the person from Microsoft that was able to get this fixed: @Raja Pothuraju , could you do the same for me?

Sridevi Machavarapu 33,820 Reputation points Microsoft External Staff Moderator

2026-01-23T00:42:35.0866667+00:00
Hello Phill Hayman,

I understand you're experiencing issues logging into your Microsoft 365 admin center due to incomplete MFA. Based on error code 399287, it appears your multi-factor authentication method is blocked because the phone number has a bad reputation.

Could you please share below details via private message so we can further assist?

Tenant ID

Phone number with country code

Country

Email address of affected user

Correlation ID

Request ID

Timestamp

Answer accepted by question author

0 additional answers

Your answer

Sridevi Machavarapu 33,820 Reputation points Microsoft External Staff Moderator

2026-01-23T00:42:35.0866667+00:00

Hello Phill Hayman,

I understand you're experiencing issues logging into your Microsoft 365 admin center due to incomplete MFA. Based on error code 399287, it appears your multi-factor authentication method is blocked because the phone number has a bad reputation.

Could you please share below details via private message so we can further assist?

Tenant ID

Phone number with country code

Country

Email address of affected user

Correlation ID

Request ID

Timestamp

Answer 1

Hello Phill Hayman,

Thank you for sharing your details(user's email address, tenant id, phone number, country code and country) with us over Private Message

I have reached out to the engineering team to unblock MFA for your account. They have now unblocked it from the backend and removed the bad reputation on it. You should be able to log in now without any issues.

Please try logging in and check if you can complete SMS authentication without any errors. Let me know if you encounter any issues.

I hope this information is helpful. Please feel free to reach out if you have any further questions.

If the resolution was helpful, kindly take a moment to click on and Yes for was this answer helpful under my answer to close this question. And, if you have any further query do let us know.