How to activate a conversation with the visitor on fb page?

Hi everyone!

The question is simple..
I have a fb page and I want to automatically start a conversation whenever a new visitor comes to my page without the need to click the 'Message' button.

Here is an example of what I want to do: https://www.facebook.com/vicino.tirane/

I'm not sure if this can be done within fb or by using an external plugin. Any help would be much appreciated! :)