How to implement "wakeup" words for rasa chatbot

Hi all. I have successfully implemented Rasa together with bert, coqui-tts and coqui-stt. I want to implement now “wakeup” words in Rasa, such that it will understand “wakeup” word and enables chatbot only after hearing that “wakeup” word. Is that possible to implement it via Rasa? If yes, how can I do that? Thank you very much for your time.