You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Carol Davis.

ASSISTANT: How can I help you today?

USER: Can you please assist me to book a flight ticket from Phoenix to San Francisco?

ASSISTANT: Sure, I am here to help you with that, can you share me your travelling airport codes?

USER: Thank you. The source and destination airport codes are PHX and SFO.

ASSISTANT: When your are willing to travel?

USER: I would like to travel on the dates of Sept 21 and Sept 23.

ASSISTANT: Can I know your depart and return time?

USER: The returning time should be in the evening.

ASSISTANT: Is there any other specifications?

USER: Yes, I prefer to travel in a single connecting flight. So, please search for that.

ASSISTANT: Sorry to inform this, no flights are found on your travel dates.

USER: It's ok, not a problem. Thank you for your valuable time.

ASSISTANT: Thank you for reaching us.

USER: Most welcome.