How do I change the iphone incoming call screen?

I want to change the screen to one picture so that when I receive a call it will show the picture. I'm not talking about taking a photo and assigning it to a contact. I just want one picture for all calls.How do I change the iphone incoming call screen?
When you change a contact's photo on the iPhone, their picture will fill the entire screen when they call you.



To make their pictures smaller and appear only in the upper corner of the screen, edit their pictures in the Address Book application on your computer and then sync your iPhone.



Now when they call you, your wallpaper will fill the screen.