You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Samantha Hall here,I want to reserve my ticket from DFW to OAK, can you please help me to book a ticket?

ASSISTANT: Ok, can I have your trip dates to go?

USER: Sure, my preferable dates of journey is from 12/15 to 12/17.

ASSISTANT: Sorry, there is no flight for you on your route.

USER: Ok, no problem. Thank you for your appreciable service.

ASSISTANT: Thanks for approaching us.