Microsoft's Siri-rivaling voice companion, codenamed Cortana, will enter beta on Lumia in April



From Techradar:

That's interesting enough, but here's the kicker: Jen Taylor, who voiced Halo's AI character Cortana in the game series, will apparently lend her pipes to the smartphone assistant.We don't know if Cortana will be her sassy self on phones, but the April release lines up with the expected Windows Phone 8.1 update, which in turn matches with Microsoft's Build 2014 conference.

  Microsoft's Siri-like voice assistant 'Cortana' may be voiced by Cortana