Issue with Authentication Methods – Phone Number Update Delay

Question

Hi,

I'm experiencing an issue with updating phone numbers under Azure B2C User → Authentication Methods → Add Phone Number.

Currently, our system calls the API to update a user’s mobile number in Authentication Methods. However, users need to check the Authentication Methods screen to confirm if the phone number has been updated.

Issues Observed:

1. The Authentication Methods screen does not update for more than 30 minutes, even if we refresh it every 3–5 minutes.
2. The screen only updates when performing F12 → "Empty Cache and Hard Refresh".
3. If a user tries to manually add their phone number, they receive the error:
   • "Unable to add Phone Number - Mobile phone method is already registered for this account."
   1. Even after refreshing, the phone number still does not appear in the interface.

Could you help us understand why this delay is happening and how we can resolve it?

Thanks!

Answer 1

Hi @Jordanaa Chong ,

Thank you for posting your query on Microsoft Q&A. I am Saiteja from Q&A will be assisting you with your query.

Based on your query, I understand that you are unable to retrieve authentication details API calls and observed delayed update on authentication methods.

1. Authentication Methods screen does not update at least 30 minutes: As you know, we have seen the recent update of MFA changing from legacy to new authentication methods. This delay might be happening due to the recent updates, and we have seen similar issues with other clients as well.
2. Is your user unable to update the phone number, you can add a custom policy to make this happen using the following link.
3. B2C does NOT store MFA phone numbers in a place exposed by MS Graph API i.e. authenticationMethods. B2C instead stores it in strongAuthentication which is a legacy property. This may also happen when you add the user MFA phone number using custom policies which does not return in MS Graph authentication phoneMethods call. This is observed as a known issue from Azure AD B2C.

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

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