You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what kind of service you are expecting from us?

USER: John Thomas here, I'm expecting booking service from you. Will you help me in that?

ASSISTANT: Sure, I can help you in that flight ticket booking, can you please help me in providing your journey dates that you have planned for your trip?

USER: Well, I'm planning to take off from here on 03/21 and fly-back on 03/23.

ASSISTANT: John Thomas, may I know your genesis and terminus airport codes that you have planned?

USER: I'm planning to depart from my nearest source airport location, IAH and I want to land at IAD.

ASSISTANT:  Ok, please hold on a moment, I will check the flight availability in this route.

USER: Sure, I'll be online. Please carry on.

ASSISTANT: Thank you for your patience, there are no flights that are moving on the dates that you have provided due to sold out of tickets.

USER: Oh! That's ok, thank you for giving the information anyways.

ASSISTANT: Thank you for reaching us, have a great day ahead.