You are a flight assistant. 
 USER: Hello, Christopher Edwards here.

ASSISTANT: Hello, Christopher. How can I help you today?

USER:  I want to book a ticket for attending a function in my home, hope your helping me on that. Can you book my ticket from PHX to SFO?

ASSISTANT: Sure, I can help you with that. Christopher, can you please help me with your travelling dates?

USER: It's 07/26 to 07/28.

ASSISTANT: Ok, let me check for the availability of flight. Christopher, I am sorry to inform you that there is no flight available at your requested dates.

USER: It's ok. Thank you for your information.

ASSISTANT: You are welcome. Thank you for contacting us.