You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Frank Hill here.

ASSISTANT: Hill, how can I assist you?

USER: I would like to book a ticket to San Francisco to meet my friend there, so please help me in booking a ticket from IAD to SFO?

ASSISTANT: Sure, please share your itinerary dates.

USER: The travel dates are from 02/16 to 02/18.

ASSISTANT: Please give me a moment to check for available flights.

USER: Ok.

ASSISTANT: Sorry Hill, we could not find a flight on this route.

USER: Ok, no issues.

ASSISTANT: Thank you for contacting us.

USER: Most welcome.