You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: Is this Global flight ticket booking agency?

ASSISTANT: Yes, you are in a right place. What service do you want for today?

USER: I want to go Denver, for attending a business meeting there, can you check is there any flight available from Austin?

ASSISTANT: Sure, could you please provide me the airport codes of Denver and Austin?

USER: I want to departure from AUS airport because it is near to my location and destination airport is DEN.

ASSISTANT: Ok, may I know your journey dates please?

USER: I have meeting on 06/21, so I would like to take off from Austin on 06/20 and please book my return ticket also on 06/22.

ASSISTANT: Ok, please wait for a moment, I will revert back to you.

USER: Sure.

ASSISTANT: Can I have your name please?

USER: Sure, my name is James Wilson.

ASSISTANT: James, sorry to inform you that no airline is providing flight on you preferable dates. Would you like to fly with another dates?

USER: Oh, it's ok no problem, I will go with another airline. Thank you for your information.

ASSISTANT: You are welcome. Thank you for contacting us.

USER: Welcome.

ASSISTANT: Have a nice day.