Microsoft confirms Cortana is coming to iPhones, Android | ZDNet

Check the article link below and this Microsoft post for more details

"The Cortana app for iPhones and Android phones will be able to do "most of the things" Cortana does on Windows 10 PCs or Windows Phones, Microsoft officials said, including setting reminders, tracking flights and the like. Everything that users enable to show up in Cortana's Notebook will show up across Windows, Android and iOS devices.

There are things Cortana won't be able to do on iPhones and Android devices, such as toggling settings, opening apps; and responding hands-free when users say "Hey Cortana," Microsoft officials said. This is because Microsoft, at least for now, doesn't have the required access to the OS elements that are required for deeper-level integration." 

Microsoft confirms Cortana is coming to iPhones, Android | ZDNet