You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Frank Smith here.

ASSISTANT: How may I help you?

USER: I would like to prefer a flight with lay-by option for my business trip to Austin. Can you book it?

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: The travel dates are from May 30 to June 01.

ASSISTANT: Please share me your source and destination codes.

USER: The airport codes are from PHX to AUS.

ASSISTANT: Do you have any other specifications?

USER: I prefer a stopover flight.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for reaching us.