The concept was to have smooth surface with hidden screen by using transparent OLED.
Unlike others, sign-phone's screen does not emit unnecessary pixel area so it gives mystic clean and unusual experience to user. whole screen display is based on functionality in use.
Back side of the phone is Solar Panel, thin white glass accepts about 80% of natural solar ray to recharge the phone.
Keypad area is also OLED pixel area. It will be shown when it is needed(number, text, icon, image etc.)