Can B2C support non-unique mobile numbers for MFA?

Question

As a user who needs to create more than one user account in B2C, I need to be able to use the same mobile number one each of them for MFA.

Is there a configuration option or strategy to get B2C to allow more than one user account to share the same mobile number for SMS MFA?

Answer 1

Hi @Mohammad Farooqi ,

Thanks for reaching out.

Azure AD B2C does not support using the same phone number for multiple user accounts for SMS MFA. Each user account must have a unique phone number associated with it for SMS MFA.

This is because SMS MFA is designed to provide an additional layer of security to verify the identity of a specific user account.

If multiple user accounts share the same phone number, it would be difficult to determine which user is attempting to authenticate and there is no point for second MFA in that scenario.

However, you can use other MFA methods such as the Microsoft Authenticator app or TOTP (Time-based One-Time Password) codes, which do not require a phone number and can be used across multiple user accounts. These methods provide a more secure and flexible way to authenticate users.

Hope this will help.

Thanks,

Shweta

Please "Accept the answer" if above answer helped you.