Microsoft 'Siri

Cortana, Microsoft's voice assistant that ups the battle against Apple's Siri and Google's Google Now, is being silenced for kids due to a government regulation.

Microsoft's Windows Phone 8.1 operating system, tested now by developers and soon to be released by wireless carriers, includes technology that allows users to issue commands by talking to their phone. The system is so unique from rivals' offerings it's triggering government rules that limit its use by anyone under the age of 13. If a user 12 or younger tries to activate Cortana, they're presented with a screen reading, 'I'm sorry, you'll need to be bit older before I can help you.'

Microsoft's voice system cannot be used by anyone under the age of 13 since it's considered an online service, which falls under the coverage of the Children's Online Privacy Protection Act, or COPPA. COPPA governs how much information a person under 13 years of age can share online without parental consent. And since Cortana takes such a personalized approach, it triggers the rule.

Cortana, named after the all-knowing guide in Halo games for Xbox, interacts with users by voice. Reviews have been glowing, as some show Cortana trounces the capabilities of the iPhone's Siri.

The success of Cortana is critical for Microsoft as it plays catch-up with Google and Apple in getting its mobile products and services into the hands of consumers. Investors are increasingly expecting smartphones to rely on more natural inputs, such as motion and voice.

Typically, online users under the age of 13 can still use certain technology if their parents grant permission. Microsoft's gaming system, Xbox Live for instance, has an online system that allows parents to turn on or off specific areas of the service for their kids. Cortana doesn't yet have that function. Cortana is still listed as being in 'beta,' or in testing mode. While Cortana is highly personalized, users can still choose what personal data are shared with the service. Microsoft did not provide an official comment as of press time.

Shares of Microsoft continue to be strong this year relative to Apple and Google. Shares of Microsoft are up 5.5%, versus the 1.2% gain by Apple and 4.2% decline by Google. Microsoft reported better-than-expected quarterly profit after the market closed, and shares are up about 2% in afterhours trading.