With the help of this solution a QR code is printed on the ticket with which the customer has the possibility to open a web page on his/her smart phone to check the actual status of the queue and see when his/her ticket has been called:
On the administrative page click on Central settings > Ticket layouts
Add a new "Barcode element"
In the text field enter the URL
http://serverhost:portnumber/qnet6/waitingarea.xhtml;?branch=1&mode=client-phone with the correct server and branch parameters. Adjust the size and position and choose "QR code" type: