Ticket by SMS
Send your order to 2027 before you board. You must have received the text message with the ticket before boarding – the time of purchase is stated in the message.
An SMS ticket cannot be forwarded. It is only valid on the phone it was bought with, and forwarding it is considered document forgery. If you want to arrange a ticket for someone else, use "buy for others" in the AtB app.
If you are having problems with the app, SMS is a good alternative.