If a number isn't in your contacts, recent calls list, or Siri Suggestions, the iPhone silences the call and sends it to voicemail. Legitimate callers (like doctors or deliveries) will leave a message; spammers usually do not.
If you want to know exactly who is calling you before you pick up, your phone’s native software usually isn't enough. You need a service that acts as a middleman to force the caller's number to be revealed. how to unblock a no caller id
Android phones vary by manufacturer (Samsung, Pixel, etc.), but most have built-in blocking features. If a number isn't in your contacts, recent
Apps like are designed specifically for this purpose. recent calls list