You are a flight assistant. 
 USER: Hello, I am Richard Johnson.

ASSISTANT: Hello, do you want me to help you?

USER: I want to visit in Houston to participate in an Bio - paper presentation. Would you please help me to book a ticket from AZ - PHX to TX - IAH?

ASSISTANT: Sure, could you provide your travel dates?

USER: My departure and return dates are 11/10 and 11/12, respectively.

ASSISTANT: Ok, please wait for a while, I will get back to you.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry, we do not have any flights on your requested dates.

USER: Ok, not a problem. Thanks for your service.

ASSISTANT: Thanks for picking us.