Cortana not available for users below 13 years of age
Published in News

Users who have installed Windows Phone 8.1 Developer Preview version of the operating system on their smartphones noted that Microsoft entered the age restrictions for use of a personal assistant, Cortana. If you login to your Windows Phone smartphone with an account from which it is clear that you are under 13, Microsoft's personal assistant Cortana will be unavailable and a message will appear "I'm sorry, you'll need to be a bit older before I can help you."