I wish to migrate adb2c but the older ad uses mfa implemented by userflow. How to get the strongAuthenticationPhoneNumber?

Question

I am following https://learn.microsoft.com/en-us/azure/active-directory-b2c/user-migration for migration and the first step is pre migration . Ive been able to migrate everything but the mfa number to the new b2c . "strongAuthenticationPhoneNumber" from the old B2C as it isnt accessible by graph?

Answer 1

You cannot access strongAuth attributes via graph api. You have to implement using custom policy. Do a find and replace for strongAuthenticationPhoneNumber with extension_whatever.

https://learn.microsoft.com/en-us/azure/active-directory-b2c/custom-policy-get-started

Use the starter pack that has MFA https://github.com/Azure-Samples/active-directory-b2c-custom-policy-starterpack/tree/master/SocialAndLocalAccountsWithMfa

If the phone numbers are already in B2C strongAuth attribute and you want to move to a new B2C tenant, then those numbers cannot be exposed. You could use a custom policy to migrate the numbers into an extension attribute on a users next sign in. Then later in time hopefully a large number have signed in and the phone numbers can be harvested into a new tenant.