MFA Blocked on Entra ID for Education Account - Error Code 399287 (Throttling / Verification Issues)

Question

MFA Blocked on Entra ID for Education Account - Error Code 399287 (Throttling / Verification Issues)

Isa Akyer 20

Hi everyone,

I am experiencing a critical MFA verification issue with my institutional Office 365 / Microsoft Entra ID account and am unable to log in.

Whenever I try to authenticate via SMS or Phone Call, I immediately receive the following error message on the screen without getting any text message or phone ring:

"We're having trouble verifying your account. Please try again."

Here are the specific troubleshooting details generated by the system:

Error Code: 399287

Request Id: <PII REMOVED>

Correlation Id: <PII REMOVED>

Timestamp: 2026-05-28T04:54:41Z

Additional Context:

I have the exact same phone number registered as a verification method on 2 or 3 other Microsoft/Office 365 accounts. SMS and calls work completely fine on those accounts, which rules out any carrier or device-specific issues.

The issue seems to be a server-side MFA throttling or number blocking mechanism specific only to this tenant account due to multiple account associations.

Clicking "Call" does not trigger any incoming phone calls either.

Since this is an education tenant, I cannot reset the MFA settings from the user side. I was advised by a community member to open this new thread for better visibility and investigation.

Could you please assist in checking what is triggering Error Code 399287 on the backend and guide us on how to clear this block?

Thank you in advance for your support.Hi everyone,

I am experiencing a critical MFA verification issue with my institutional Office 365 / Microsoft Entra ID account and am unable to log in.

Whenever I try to authenticate via SMS or Phone Call, I immediately receive the following error message on the screen without getting any text message or phone ring:

"We're having trouble verifying your account. Please try again."

Here are the specific troubleshooting details generated by the system:

Error Code: 399287

Request Id: 303aae45-e539-4c88-a759-85f873366c00

Correlation Id: 3083e56e-9a22-433b-9ffc-b6a9d94dc7ca

Timestamp: 2026-05-28T05:41:14Z

I have the exact same phone number registered as a verification method on 2 or 3 other Microsoft/Office 365 accounts. SMS and calls work completely fine on those accounts, which rules out any carrier or device-specific issues.

The issue seems to be a server-side MFA throttling or number blocking mechanism specific only to this tenant account due to multiple account associations.

Clicking "Call" does not trigger any incoming phone calls either.

Since this is an education tenant, I cannot reset the MFA settings from the user side.

Could you please assist in checking what is triggering Error Code 399287 on the backend and guide us on how to clear this block?

Thank you in advance for your support.

@Raja Pothuraju

Shubham Sharma 17,930 Reputation points Microsoft External Staff Moderator

2026-05-28T05:39:06.42+00:00

Isa Akyer

Welcome to Microsoft Q&A Platform.

I understand you're experiencing issues logging into your Azure account due to 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 send requested via private message so we can further assist?

Thanks

Answer accepted by question author

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Your answer

Shubham Sharma 17,930 Reputation points Microsoft External Staff Moderator

2026-05-28T05:39:06.42+00:00

Isa Akyer

Welcome to Microsoft Q&A Platform.

I understand you're experiencing issues logging into your Azure account due to 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 send requested via private message so we can further assist?

Thanks

Answer 1

Isa Akyer

Thank you for your patience

I’ve reached out to the engineering team regarding the MFA issue on your account. They have now unblocked it from the backend and cleared the bad reputation associated with it. You should be able to log in to the Azure Portal without any issues.

Please try signing in and verify if you can complete SMS authentication successfully. Let me know if you encounter any problems.

As a best practice, I recommend registering the Microsoft Authenticator method for your account instead of relying on SMS. SMS and voice call authentication methods are more vulnerable to IRSF attacks (telephony fraud) and are generally less secure.

For better practice, I recommend registering with Microsoft Authenticator method to your account instead of SMS method as these SMS/Voice telecom auth methods are susceptible to IRSF attacks telephony fraud.

If the resolution was helpful, please take a moment to accept the answer and upvote it 👍 to make it helpful to the community.

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