Tinitell
Tinitell is a new wrist based cellular phone for kids. It's first paired with your smartphone (iPhone or Android). You can then load contacts into it for voice calling. If you don't want to use voice dialing, you can use the volume buttons to have it read your contacts back to you (Mom, Dad, etc). While Tinitell is capable of receiving calls from any number, you can limit the numbers to a pre-defined list. You can also manage it from the Tinitell website as well.
The battery will last a week on standby and has 60 minutes of talk time. It will work with any GSM sim card. It works in every country except North Korea, South Korea, and Japan. With built in GPS and voice recognition, this is ideal for keeping track of your kids. It has a water resistant design that is also safe to use in the sandbox.
You can pre-order your Tinitell for $129.