KYC-Match: Matches the subscriber or phone user data?

[sfnuser]

Problem description
This is more of a question rather than an issue - just to understand interpretations

API says An endpoint to verify the matching of a number of attributes related to a mobile phone user identity against the account data bound to their phone number

When this api is accessed, what is considered as the identity when an access token is issued - subscriber or the phone number?
Unlike some of the other device oriented APIs, this API returns the user details - are they associated with the subscriber or the phone number? For e.g a subscriber can have multiple phone numbers (all operated by the same subscriber) or the case where the multiple phone numbers are operated by different users (a family head being the subscriber and family members operating the phone or business account use cases)

What will be the sub field of the ID token returned - it identifies the subscriber or the phone user?