Thank you for your kind response. Let me explain what I’m trying to implement in detail. I am creating a contact app that provides users with the ability to manage additional information (such as importance levels or complaints) for their contacts. The feature I want to implement is to display this additional information on the incoming call screen when receiving a call from someone saved in the contacts. For example, if the system contact is saved as “Mr. Kim Minsu” but in this app, it’s saved as “Importance 5 Kim Minsu,” I want the incoming call screen to display “Importance 5 Kim Minsu” when the call is received. According to the documentation in https://developer.apple.com/documentation/callkit/identifying-and-blocking-calls, it seems that the Call Directory is only referenced for phone numbers that are not in the system contacts. Is that correct? I am wondering if it’s possible for my app to reference contacts in the system contacts as well.