There have been reports of the white iPhone 3GS discolouring due to overheating. MACNN reports that the rear of the case turns a light shade of pink after suffering from the overheating problem. Phones suffering from this problem continue to function as expected despite user concerns at the amount of heat being generated around the location of the battery. Users with concerns should call Apple at 1-800-275-2273, or use their online iPhone support resources.