Step 3. Now, tap on the name of the contact at the top center of the message window to reveal the contact details.
Step 4. Scroll to the bottom of the details and tap on the ‘Block this caller’ option.
The feature to block contacts is pre-built into iOS and you do not need any third party application to get the job done. There are some apps out there that claim to help you manage your contacts, but to be perfectly honest, you do not need them on your iPhone.
