Open the Phone app
Tap the Recent calls or Contacts tab
Tap the number you want to block
Tap More options or the three-dot menu
Select Block number or Block/report spam
Confirm the block
Open the Phone app
Tap the three-dot menu
Go to Settings
Tap Blocked numbers
Tap Add a number
Enter the number
Tap Block
Open the Messages app
Open the conversation from the number
Tap the three-dot menu
Select Block number or Block contact
Confirm the block
Open the Contacts app
Select the contact
Tap More options
Choose Block contact
Confirm the block