Why do I sometimes see my child talking to his Nintendo DS?
One of the features of the Nintendo DS is a built-in microphone. Some games call for players to speak into the microphone or blow into the microphone to affect game events.
The microphone can also be used to communicate (Voice Chat) with others while playing certain DS games via Nintendo Wi-Fi Connection. A person can only speak to another player with whom they’ve shared a special numeric Friend Code. Because of this, your child will not be able to talk via Voice Chat to anyone whom he does not know.