Azure AD B2C - remove country code options on Phone sign up page of sign up flow

To remove the country code options from the phone sign-up page in the Azure AD B2C sign-up flow, you need to customize the user journey by editing the corresponding custom policy. You'll need to make changes to the user interface (UI) customization and the user journey to achieve this. Here's a high-level overview of the steps:

1. Create a Custom Policy:

   • If you haven't already, create a custom policy in your Azure AD B2C tenant. You can do this through the Azure portal by following the instructions in the Azure AD B2C documentation.

2. Customize the User Interface:

   • Locate the file that defines the user interface for the sign-up page. It is typically named SelfAsserted-LocalAccountSignin-Email or SelfAsserted-LocalAccountSignin-Phone.
   • Customize the file to remove the country code options from the phone sign-up page. You can use custom HTML and CSS to modify the appearance and layout of the page.

3. Update the User Journey:

   • The user journey defines the flow of the user through different steps in the sign-up process. You need to update the user journey to use your customized user interface.
   • Find the <UserJourneyBehaviors> element in the custom policy file and look for the user journey that corresponds to the sign-up flow. It usually starts with <UserJourney Id="SignUpOrSignIn">.
   • Inside the user journey, locate the step that uses the SelfAsserted-LocalAccountSignin-Phone or SelfAsserted-LocalAccountSignin-Email technical profile.
   • Update the ContentDefinitionReferenceId attribute of the step to point to your customized user interface file.

4. Upload and Test:

   • After making the changes, upload the updated custom policy to your Azure AD B2C tenant through the Azure portal.
   • Test the sign-up flow to ensure that the country code options are no longer shown on the phone sign-up page.

It's important to note that modifying Azure AD B2C custom policies requires a good understanding of the policy language and the specific elements used in the user journey. Care should be taken when making changes to avoid breaking the sign-up flow or introducing security vulnerabilities.

Additionally, Microsoft may update the structure of custom policies or introduce new features over time. Therefore, I recommend referring to the official Azure AD B2C documentation and the Azure AD B2C community for the latest guidance and best practices regarding custom policies.