The problem with Hiya as I understand it is that it is limited by CallKit list size. I'm not 100% sure of this, but I think Apple's implementation requires a fully offline call list so that your phone calls are not sent to a public server and could be logged. This means that the number of phone numbers that Hiya can call spam must be downloaded ahead of time and loaded into CallKit. What I see often is that a phone number will not be flagged as spam, but if I query the number through the app later, it will correctly show it as spam. Someone correct my if I am wrong, but I think this is the problem.