You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I need a direct flight for my journey which returns in the evening from my destination point Dallas in the month of April. Can you help me in booking my flight ticket?

ASSISTANT: Ok, may I know your travelling airport codes?

USER: Sure, my travelling dates are Apr 18 and Apr 20.

ASSISTANT: Can you please mention your travelling codes?

USER: My travelling codes are SFO and DFW.

ASSISTANT: May I know your name?

USER: Sure, my name is Paul Hill.

ASSISTANT: Do you have any other preference?

USER: No.

ASSISTANT: Sorry, no flights found on your route.

USER: Not a problem, anyways thank you for the information.

ASSISTANT: Thank you for connecting with us.