Should I call the guest or send a message now? I am sincere to every customer and won't play any tricks. What should I say?

You can take care of both and see what kind of customers. Different types of customers should use different methods, but don't irritate your customers. If you want to choose between the two, I think it is better to contact by phone, because it is convenient to communicate and get more effective information from the tone and words of the other party. This is just my opinion. But in sales, there is no fixed method. As long as you think this method is suitable for you and more effective, then you can do it.