How does Apple 7p set a background for everyone?

1: Click the "Photo" icon from the screen desktop to enter;

2: Click on a picture to be set as an incoming call photo to enter, and then click the Share button in the lower left corner;

3: Click "Assign to Contact";

4: After selecting the designated contact from the address book, an effect picture will be returned, and then click the "Select" button to complete the setting;

5. Contacts can call and see the actual effect.