It covers setting full-screen contact photos both with new photos and existing contact photos.
The instructions in this article apply to iPhones running iOS 8 to iOS 16.
If you’re running iOS 17 or higher, seeHow to Make a Contact Poster on iPhone.

To get full-screen photos, go toSettings>Phone>Incoming Calls>Full Screen.
Open theContactsapp and tap the contact’s name.
On the contact’s information screen, tapEdit.

TapAdd Photo(or tapEditto replace an existing photo).
Use the iPhone camerato take a photo or choose one from your Photos app.
Move and scale the photo to fit it in the circle.

TapChooseorUse Photo,depending on whether it’s a new photo or a photo you already have.
If your existing contact photos appear as small, circular images, getting them full screen requires another change.
OpenthePhoneorContactsapp, then tap the contact name.

SelectEditunderneath the current photo.
Movethe existing photo a little.
You don’t need to edit it.
The next time this person calls you, you’ll see the photo in full-screen mode.
One downside to this technique is that there’s no setting to control this feature for all your contacts.
You have to repeat this process for every photo you want to be full screen for incoming calls.
FAQ
Toblock a caller on iPhone, launch the Phone app and selectRecents.
Tosilence an unknown caller, selectSettings>Phone>Silence Unknown Callersand then tapSilence Unknown Callers.
you might also use athird-party spam-blocking appto filter unwanted calls.
When you make calls now, recipients won’t see your caller ID.