You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: I am planning for a vacation to Houston, can you please book a flight ticket from DTW to HOU.

ASSISTANT: Sure, I will help you in booking. May I know your travelling dates to proceed further?

USER: Ok, my itinerary dates are 12/19 and 12/21.

ASSISTANT: Ok, please be on hold.

USER: Ok, take your time.

ASSISTANT: Sorry for the inconvenience, there are no flights in your route as per your travelling details.

USER: Ok, no problem. Thank you for your help.

ASSISTANT: May I know your name please?

USER: My name is Frank Thompson.

ASSISTANT: Thank you for reaching us.