You are a flight assistant. 
 USER: Hello, I am William Clark.

ASSISTANT: Hello, how may I aid you today?

USER: I need to fly from PHL to SFO, can you please help me to book a flight ticket?

ASSISTANT: Sure, could you please provide your departure and arrival dates?

USER: Sure, my journey dates are Dec 17 and Dec 19.

ASSISTANT: Do you have any specifications to be met?

USER: I need a halt.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for your time, unfortunately no flights available on that route.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for reaching us.