SMS/Voice Authentication Available Despite Being Disabled in Authentication Methods Policy

Dey, Dipronil 0 Reputation points
2026-09-30T14:53:16.0433333+00:00

We have configured the Microsoft Entra ID Authentication Methods Policy and disabled SMS and Voice calls authentication methods. The tenant's legacy authentication methods policy migration status is also Complete.

However, we are observing different behavior for cloud-only and AD-synced users:

  • For cloud-only users, the SMS/Voice options are not available under Security Info.
  • For some AD-synced users, options such as Voice call and Hardware token are still visible under Security Info.
  • For an AD-synced user, we are able to add a mobile phone number and successfully use the phone number for MFA.
  • Per-user MFA is set to Disabled for the affected user.
  • SMS and Voice authentication are disabled in the current Authentication Methods Policy.
  • Legacy MFA/SSPR authentication method migration is showing Complete.
  • We are also synchronizing attributes such as mobile and telephoneNumber from on-premises Active Directory.

Question:

Why is an AD-synced user still able to register and use a mobile phone for MFA when SMS/Voice authentication methods are disabled in the Authentication Methods Policy and the legacy policy migration is complete?

Could you please confirm:

  1. Whether synchronization of the mobile or telephoneNumber AD attributes can cause a phone number to become usable as an MFA authentication method.
  2. Which Entra ID policy or configuration could allow SMS/Voice authentication in this scenario.
  3. How we can completely prevent SMS/Voice registration and authentication for these AD-synced users.

We can provide screenshots of the Authentication Methods Policy, user's Authentication Methods page, Security Info page, and Sign-in Logs/Authentication Details if required.

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Microsoft Security | Microsoft Entra | Microsoft Entra ID
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  1. AI answer

    2026-09-30T14:53:42.6433333+00:00

    The supported explanation is that legacy settings can still affect what users see and use if they were not fully cleared before migration, even when migration shows Complete.

    What is confirmed:

    1. Authentication Methods policy is the recommended control plane It is the policy used to enable or disable methods such as SMS and Voice calls for all users or specific groups.
    2. Legacy MFA and SSPR policies existed separately and mapped phone-based methods differently
      • In legacy SSPR, Mobile phone allowed either voice calls or text message.
      • Office phone allowed voice calls only.
      • In the Authentication Methods policy, these map to SMS and Voice calls, with Office phone controlled under Voice calls > Configure.
    3. A completed migration does not by itself prove legacy phone options were removed correctly before completion A matching Microsoft Q&A resolution describes the exact pattern where migration was marked completed, but legacy verification options and password reset authentication methods had not been unchecked first. The fix was to set migration back to In-progress, clear the legacy verification and password reset authentication options, and then complete migration again.
    4. Only the converged registration experience is aware of the Authentication Methods policy If registration experience differs between users, that is a relevant factor because users not in the converged registration experience do not see methods according to the Authentication Methods policy.

    What is not confirmed by the available documentation:

    • There is no support here that syncing mobile or telephoneNumber from on-premises AD automatically makes that number a usable MFA authentication method.
    • There is no support here that AD-synced users are intentionally treated differently from cloud-only users for SMS/Voice when the same Authentication Methods policy applies.

    Based on the supported guidance, the most likely policy/configuration path allowing phone-based MFA in this scenario is:

    • residual legacy MFA/SSPR phone settings still being effective, especially Mobile phone or Office phone settings from legacy SSPR/MFA, despite migration showing Complete; and/or
    • a registration experience mismatch, because only the converged registration experience honors the Authentication Methods policy.

    To fully prevent SMS/Voice registration and use, the supported remediation path is:

    1. In Entra ID > Authentication methods > Policies, verify SMS and Voice calls remain disabled for all relevant users and groups.
    2. Review the old policy locations:
      • Entra ID > Multifactor authentication > Getting started > Configure > Additional cloud-based multifactor authentication settings
      • Entra ID > Password reset > Authentication methods
    3. If legacy phone methods were left enabled before migration, use the documented Q&A resolution:
      • change migration state back to In-progress
      • uncheck all legacy verification and password reset authentication options related to phone methods
      • complete the migration again
    4. Confirm users are on the converged registration experience, because otherwise the Authentication Methods policy is not the source used for what they can register.

    For the specific items raised:

    • Can synced mobile/telephoneNumber attributes cause MFA usability? Not established by the available documentation.
    • Which policy could still allow SMS/Voice? The supported answer is the legacy MFA/SSPR phone settings if they were not fully cleared before migration, plus possible impact from not using the converged registration experience.
    • How to completely block SMS/Voice for affected AD-synced users? Disable SMS and Voice calls in Authentication Methods policy, clear legacy MFA/SSPR phone options, then complete migration again after those legacy options are removed.

    References:

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