Open the Phone app
Tap Recents, Favorites, or Voicemail
Find the number you want to block
Tap the info icon next to the number
Scroll down and tap Block this Caller
Tap Block Contact to confirm
To block a saved contact, open Contacts, select the contact, tap Block this Caller, then confirm
To block unknown or spam numbers, go to Settings
Tap Phone
Tap Silence Unknown Callers to reduce unwanted calls
To block messages, open the conversation in Messages
Tap the contact or number at the top
Tap Info
Tap Block this Caller
To manage blocked numbers, go to Settings
Tap Phone
Tap Blocked Contacts