Based on your request, you are likely looking for one of two things:
To actively identify if a number is a "spam block" risk, you need an app that maintains a database of spam numbers.
Note for iOS 18+: You may need to go to > Apps > Phone > Blocked Contacts . how to check block number in iphone
Tap Add New at the bottom of the list to block a contact from your address book.
Frustrated, she tapped . She found “Leo DO NOT ANSWER” easily. She opened his card and scrolled all the way down. There it was: Block this Caller —but the button was blue, meaning he was blocked. That confirmed it, but it didn’t show her other blocked numbers. She needed the master list. Based on your request, you are likely looking
She tapped it.
Go to Settings > Phone > Blocked Contacts . Frustrated, she tapped
You can also find this same list by going to Settings > Messages or Settings > FaceTime and tapping Blocked Contacts . Managing the List: