Issues with bad phone number reputation when selecting SMS as MFA method.

Question

Hello,

I have previously had this same issue and posting a question here solved it for me last time. So I am once again asking for support.

I have recently created a tenant and three users with it, they are unable to use their phone numbers via SMS as a second factor for authentication. The errors are the following:

Error Code: 399287

Request Id:

Correlation Id:

Timestamp: 2026-03-23T09:56:54Z

Error Code: 399287

Request Id:

Correlation Id:

Timestamp: 2026-03-23T09:56:59Z

Error Code: 399287

Request Id:

Correlation Id:

Timestamp: 2026-03-23T09:57:02Z

If there exists a manual way to solve this issue of "Bad phone number reputation" I would kindly like to ask for instructions on how to proceed. Otherwise I know the forum Moderators can help me and I once again kindly ask for your help.

TIA

Answer 1

Hi Love Givik ,

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 to the Azure Portal 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.

If this answers your query, do click Accept Answer and Yes for was this answer helpful, which may help members with similar questions. If you have any other questions, let me know in the “comments” and I would be happy to help you.