Cortana - named after an AI character from Microsoft's popular Halo series of videogames - has already been available on Windows Phone 8 devices for around a year, and an updated version is expected to arrive on desktops with the launch of Windows 10 this autumn, Reuters reports.
People familiar with the project have stated to the news provider that this will be shortly followed by a standalone app for both iOS and Android-powered smartphones and tablets.
Reuters suggested this will be part of chief executive Satya Nadella's strategy to open up Microsoft software so it will be available on any device or platform, as opposed to attempting to force consumers to rely on Windows products.
The next version of Cortana will use research gained from Microsoft's Einstein artificial intelligence project. This will help the software understand where a user is, what they are trying to do, and what time it is in order to provide the most useful information.
For instance, Cortana could tell a mobile phone user when to leave for the airport, days after it read an email and realised the user was planning a flight. The tool would then automatically check flight status, determine where the phone is located using GPS, and check traffic conditions to make sure the individual gets to the airport on time.
While none of the individual steps are revolutionary, Microsoft says creating an artificial intelligence that can stitch them all together marks a breakthrough in usefulness.
Eric Horvitz, managing director of Microsoft Research and a part of the Einstein project, said: "This kind of technology, which can read and understand email, will play a central role in the next roll out of Cortana, which we are working on now for the fall time frame."