You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: I am Helen carter. I got an admission in University of Houston so I need to attend for certification process. Can you book a ticket from AZ-PHX to TX-IAH?

ASSISTANT: Sure, can you please share your trip dates?

USER: My trip dates are 05/13 and 05/15.

ASSISTANT: Do you have any specifications?

USER: I need a direct flight.

ASSISTANT: Please wait for a while. Sorry, there is no direct flight found on your given details.

USER: Thank you for your help.

ASSISTANT: Thanks for choosing us.