It's very simple!
When an operator receives a new inquiry, it will appear as Pending.
By clicking on the query, the conversation is displayed and by simply clicking on the Attend button at the bottom of the page, the query is answered, and you can start chatting with the user.
See example images below👇
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You can also see how to close an inquiry here 👉 How to close an inquery here👉 EN_¿Cómo cerrar una consultainquiry?