We have been hearing rumors that Microsoft could introduce a new voice assistant feature in their upcoming Windows Phone 8.1 update called Cortana, named after one of the characters from their Halo video game franchise. Not much is known about the voice assistant, at least until Chinese website CTechcn came forward with some new information about the upcoming feature. According to them, Cortana will be similar to the Moto X and how it will have an always-on feature, meaning that it will always be listening for your voice compared to Siri where you will have to activate it in order to use it.
Cortana has also been said to be able to unlock your phone using just your voice, and if you thought that was a little dangerous, fret not as it will be unique to your voice, meaning that if someone else tried to unlock it with their voice, it would not work. Cortana is also expected to be open to developers so that they can integrate it with their apps which would be interesting, especially given that other voice assistants such as Siri remain closed to developers. In any case word has it that the feature is in the final testing phase so hopefully it will be done in time to ship with the Windows Phone 8.1 update.