You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: Christine Turner here. I would like to book a ticket from IAH to OAK, can you please help me with that?

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

USER: The travel dates are from 09/21 to 09/23.

ASSISTANT: Let me check for the availability of flight.

USER: Ok.

ASSISTANT: Christine, there is no flight available at your requested dates.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for contacting us.