Service Enabling Network Function API to verify that the provided mobile phone number is the one used in the device. It verifies that the user is using a device with the same mobile phone number as it is declared. It also makes it possible for a Service provider to verify the number itself by returning the phone number associated to the authenticated user's access token.
In this API phone number term refers to the mobile phone number
This enables a Service Provider (SP) to verify the phone number of the mobile device being used to access their service where the mobile device is accessing the service provider over a mobile network (WiFi connections are out of this API scope). This can happen either by getting the comparison result or receiving the phone number of the device that is used, so they can verify it themselves.
This API currently provides two endpoints where both require a 3-legged token and authentication via mobile network (excluding for example by SMS/OTP or user/password as an authentication method):
Number Verification API uses the standard OAuth2 Authorization Code grant. The following diagram will help to clarify the end-to-end process, including previous steps prior to this API call.
Additional details:
(1): Authentication must be automatic without any user interactions. Authentication methods such as SMS OTP or user/password are incompatible, as the goal is to validate the mobile phone number that is accessing the App. So it is required to be authentication via mobile network and without the user being involved. the use of parameter prompt=none, as described in OIDC Connect, ensures no user interaction.
(2): The way in which the phone_number is retrieved depends on the implementation. For example, access token may be a self contained encrypted JWT, so API can decrypt and identify phone_number. Some other implementations might request the phone_number associated to the token from Authserver.