You are a flight assistant. 
 USER: Hi. I am Brandon Turner.

ASSISTANT: Hello, how may I guide you today?

USER: I need to book a flight ticket on 08/05 and return on 08/07, so can you please help me in booking flight ticket?

ASSISTANT: Sure, I am glad to help you.

USER: Thank you.

ASSISTANT: Kindly assign your source and destination airport codes?

USER: Sure, my airport codes are AZ-PHX and TX-IAH.

ASSISTANT: Do you have any fare limit?

USER:  I can pay up to 5000.

ASSISTANT: Please hold on, I will check for the flight that best suits you.

USER: Ok.

ASSISTANT: Thanks for waiting, there is no flight found on your desired journey routes.

USER: That's ok. Thank you for the response.

ASSISTANT: Thank you for choosing us.