First, there was Siri, and she was the first phone-based virtual assistant. Then Microsoft released Cortana, a virtual assistant with more capabilities than Siri, but requires users to have a Windows phone to access her system. However, that exclusivity was only meant to last for a short time.

The Redmond, Wash.-based company is reportedly looking to bring a Cortana app to Apple and Android phones in the near future. Eric Horvitz, managing director of Microsoft Research, told Reuters that such an app was currently being developed by Apple's team.

"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," Horvitz said. 

However, Cortana is only the first version of the virtual assistant. Microsoft is reportedly working on a smarter virtual assistant codenamed Einstein, which will reportedly use a higher level of AI to complete its tasks, as well as receive new capabilities.

This move shouldn't surprise anyone, though. According to Reuters, Cortana and Project Einstein "represent a new front in CEO Satya Nadella's battle to sell Microsoft software on any device or platform, rather than trying to force customers to use Windows."

Historically, Microsoft has emphasized how Cortana was able to learn and anticipate the needs of its owner, as compared to Siri, which is a response-based software that has no learning curve.

That doesn't mean that Apple isn't fighting back for virtual-assistant dominance. Apple will empasize putting Siri compatible with Carplay and Homekit, as well as syncing it with Microsoft's Bing engine.

Cortana is named after a popular artificial intelligence from the "Halo" video game series.