You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: Daniel Smith here.

ASSISTANT: How may I help you?

USER: I would like to visit Houston to meet my old friend there, can you please help me out with booking of a flight ticket to go there?

ASSISTANT: Sure, help me with the trip dates?

USER: Thank you, I am planning to leave on 04/06 and please book my return ticket on 04/08.

ASSISTANT: May I know your airport abbreviates?

USER: I will prefer ATL and IAH as my origin and destination airport codes respectively.

ASSISTANT: Sorry, there were no flights running in your preferred dates.

USER: Oh! Sad to hear that. Anyway, I will another alternative to go there. Thank you for the information.

ASSISTANT: Thank you for reaching us. Have a nice day.

USER: Welcome.