From the version 1.8.0 we support Pusher for sending real time notifications for new orders and call waiter option. To setup the plugin follow this article:
After you enable this plugin you will need to enable Call Waiter feature in the Settings page (Setup menu).
Now everything is ready.
The menu Call Waiter in the header will appear for the customers.
When the customer click on that button the popup will appear with option for selecting table from drop down menu.
When the customer finish this process the notification will appear in the restaurant owner dashboard on the right bottom corner.