You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jeffrey Campbell.

ASSISTANT: How may I help you?

USER: Can you please book a flight ticket from IAH to DFW?

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: Sure, I need to travel on dates of Dec 21 and Dec 23.

ASSISTANT: Do you have any other specifications?

USER: I would like to depart in the afternoon time only.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for reaching us.