https://qz.com/1272522/how-to-make-alexa-the-default-assistant-on-an-android-phone/

If you miss barking orders at your home Alexa device while you’re on the move, you’re now in luck.

That is, if you have an Android phone. Many core parts of the Android operating system can be customized, from what app you use for messages down to the program you use to display apps on the home screen. And you can now change the default voice assistant on an Android phone to Amazon’s Alexa or Microsoft’s Cortana, the Verge recently uncovered.