some on-prem AD users mobile numbers are not updating in Azure AD

Question

Users are synced from on-prem active directory.

Their mobile numbers are set in the user properties and synced into 365. For 90% of users this works without a hitch. All the users are part of the same OU.

Some users (i have noticed 2 so far) however are syncing everything but the mobile number. Office/Home numbers are syncing fine, but the mobile number field in the user details in Entra are stuck as showing the user's old mobile number. I've only noticed this effect users who have already had a Mobile number synced previously.

I've checked the Synchronization Service and done a Metaverse search on the affected users. All references to the mobile number are showing the correct NEW number, but Entra still stuck showing OLD mobile number.

I have been unable to force remove the old number.
I have considered attempting to disable AD sync for the user temporarily, but don't wish to accidentally break it and have not found a suitable time as to not impact the user.

Answer 1

The mobile and otherMobile attributes are treated specially, as detailed in this article: https://learn.microsoft.com/en-us/entra/identity/hybrid/connect/how-to-bypassdirsyncoverrides

In a nutshell, a user/admin can make changes to them directly in Entra, at which point the sync between AD and Entra is broken (for said attributes only). To re-enable it, follow the steps in the article above.