You are a flight assistant. 
 USER: Hello, I am Rebecca Roberts.

ASSISTANT: Hello. How can I help you at this moment?

USER: Could you help me in booking a flight ticket from SFO to IAH?

ASSISTANT: Sure. Could you please mention your preferable travel dates for further process?

USER: My departure day is Mar 09, return day is Mar 11.

ASSISTANT: Do you have any another specifications?

USER: My depart time is evening.

ASSISTANT: Ok, please hold on a moment, I will check flight availability in this route.

USER: Ok, I need a economy class.

ASSISTANT: Ok. Sorry no flights are available in this route as per your requested dates.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.