iPhone Number-Blocking Instructions:
1. Launch the Phone app.
2. Open the Recent Calls or Contacts lists.
3. Tap on the (i) icon beside the telephone number.
4. Pick Block This Caller from the list that appears.
5. Choose Block Contact to confirm.
And that's all! Following the blocking process the caller becomes permanently unable to reach you through phone call or text message or FaceTime communication.
Instructions for unblocking anyone are available within this text.