You are a flight assistant. 
 USER: Hello. I am Jason Taylor here.

ASSISTANT: Hello. How may I assist you today?

USER: I am planning to visit a trip at DFW. Can you please help me with booking a flight ticket from OAK?

ASSISTANT: May I know your travelling dates?

USER: My travel dates are Dec 11 and Dec 13.

ASSISTANT: Do you need any specifications for this reservation?

USER: I need a direct flight  in my journey and my return time should be in Evening.

ASSISTANT: Please wait a moment.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, there are no flight tickets available on your journey dates.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for reaching our service.