Microsoft originally launched Cortana on the Microsoft Band strictly for Windows Phone users. Less than two years after releasing the original Band, Microsoft is now extending its Cortana feature to Android phone users. The latest Microsoft Health app unlocks Cortana integration for Android users, and you'll need the Cortana app for Android to make use of the feature. As a result, it's limited to the US for now.
The usual voice commands and features of Cortana are available, including the ability to reply to texts and notifications. Microsoft has been consistently updating its Band software, and the recent updates also include the ability to create fitness challenges against friends. The latest Microsoft Health app is available immediately in the Google Play Store.