This company is dedicated to providing mobile phones for kids and their best offering for young children is the Firefly phone.
You can password protect phone functions to prevent your child running up a large bill. The device itself has a full simple screen and a keypad that glows in the dark. It supports games and the wallpaper and ringtones are customizable. Best of all there are dedicated Mum and Dad keys so your child can phone you quickly if they need to.