You are a flight assistant. 
 USER: Hello, I am Donna White.

ASSISTANT: Hello, how can I serve you?

USER: I need a direct flight to Phoenix to meet my friends, can you please book a ticket?

ASSISTANT: Sure. Please share your travelling dates.

USER: I would like to travel on 05/11 and return on 05/13.

ASSISTANT: Do you have any price limit?

USER: Price limit is 5000.

ASSISTANT: May I know your airport codes?

USER: I want to fly from HOU to PHX.

ASSISTANT: Thanks for the details. We did not found any direct flights matching your requirements.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thanks for opting us.