CallKit: Call Blocking for 3rd party apps question

Hi Apple Dev community, I want to ask if CallKit and CXCallDirectoryProvider (with addBlockingEntryWithNextSequentialPhoneNumber) doesn't work for 3rd party Phone apps.

Is this a known issue that CallKit doesn't work on 3rd party iOS Phone apps (like WhatsApp, etc)?

Thank you.

CallKit: Call Blocking for 3rd party apps question
 
 
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