In order for any phrase recognizers to recognize a phrase, PhraseRecognitionSystem must be running. Starting a phrase recognition will automatically start the phrase recognition system if it's stopped.
Phrase recognition system cannot be started if there are any dictation recognizers active.
Phrase recognition system is currently only functional on Windows 10. Use PhraseRecognitionSystem.isSupported property to determine whether speech recognition is supported on the system that the application is running on.