Android users that say “Hey Cortana” to their phones will be greeted with nothing but silence, starting today. Microsoft has announced that they are disabling the hands-free feature due to it conflicting with Android voice search. The move is said to only be temporary, but the company hasn't stated just how long it will remain disabled.
The issue lies with the fact that Android devices already have a hands-free search feature. Just say “OK Google” and it will search for whatever you say next. The trouble is that if you have both enabled, your phone might not be able to keep up.
Since the hands-free commands haven't been implemented into the iOS version of the app, you're going to have to stick to a Windows phone to get it. We'll let you know when it rolls back out for Android devices.