There are situations when a chatbot can't assist a user's request. So, the last one gets an "I'm afraid I can't answer your question. My teammate will contact you shortly" message. The control over chat goes to human agents, or they answer user questions later via email, messenger.
There are four scenarios when you should consider implementing Chatbot to human fallback:
Taking over the conversation, the agent sees the chat history and the context of the request.