Unable to complete MFA on a guest-admin directory — error 399287, Authenticator lost, sole admin

Uri 40 Reputation points
2026-06-08T16:11:09.6466667+00:00

I am locked out of MFA for one tenant where I am the sole guest

administrator.

  • Signing in and completing MFA to my home directory works fine. The problem is only when I use the same account to access an external directory where I'm a guest admin.
  • On that directory, "Sign in another way" offers SMS and voice call, but BOTH fail instantly with error 399287 (telephony "bad reputation" block — no code sent, no call placed).
  • My Microsoft Authenticator device was lost and can't be recovered, so I have no usable method left on that tenant.
  • I am the sole administrator in that tenant, so no other admin can reset my MFA.

Note: a related ticket for a different tenant of mine was just resolved

by your team via this same process. This request is for a separate

tenant (one tenant per ticket).

Requested fix: remove the phone bad-reputation block and/or issue a

Temporary Access Pass so I can sign in once and re-register a fresh

Authenticator + phone on this tenant.

I can verify account/tenant ownership privately (callback, email, DNS).

Happy to share the tenant ID, UPN, and phone number by private message.

Microsoft Security | Microsoft Entra | Microsoft Entra ID
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Answer accepted by question author
Sridevi Machavarapu 33,820 Reputation points Microsoft External Staff Moderator
2026-06-08T16:14:16.46+00:00

Hello Uri,

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 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.

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

If this answers your query, do click 210246-screenshot-2021-12-10-121802.png 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.

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