You may block calls on your iPhone in a variety of ways. You may use the Do Not Disturb (DND) functionality to block all calls or select numbers. Here's how to do it:

1. Using Do Not Disturb to block all calls

You can't block an unknown caller (No Caller ID), but you may manually turn on Do Not Disturb and set it to 'Only allow calls from your contacts list.'

Here's how to do it:

1. From the Home screen, choose Settings.
2. Select Do Not Disturb from the menu.
3. Toggle the switch next to Manual to manually activate Do Not Disturb.
4. Toggle the switch next to Scheduled to activate Do Not Disturb at a certain time, then press to alter the start and finish times.
5. Tap Accept to allow calls from certain categories of persons. and select the desired groups.
6. To all repeat callers to ring through, toggle the switch next to Repeat

The second call must be made within three minutes after the first.

1. Blocking Individual Contacts or Phone Numbers
2. From the Home screen, choose Phone.
3. Select Recents or Contacts from the drop-down menu.
4. Next to the person or phone number you wish to block, tap the Information button I
5. Scroll to the bottom of the Contact Information screen and pick the 'Block this caller option.
6. To confirm, tap Block Contact.

• If you wish to unblock the number, go to the Contact Information page and click 'Unblock this Caller.' Alternatively, navigate to Settings-> Phone-> Call Blocking & Identification->Edit-> press the (-) icon next to the number or contact you want to unblock, then confirm by tapping Unblock.
• To see the complete list of contacts and phone numbers that you have blocked, go to Settings-> Phone-> Call Blocking & Identification. You can also add a new Block Contact or Edit (Unblock) number from within Settings