Trenitalia Website
Reservations
On the Trenitalia website, you can purchase reservations including supplements for the FIP Coupon for Le Frecce and other long-distance trains.
The DIRITTO AMMISSIONE fare can be used for this. Although it is not explicitly for FIP, it is accepted. You will also need a FIP Coupon to use it. Business and Executive class cannot be used with FIP. The correct fare would be Biglietti Gratuiti FS 1/2 Classe, which covers the price difference between regional and long-distance trains. This fare is usually more expensive than DIRITTO AMMISSIONE, but cannot be purchased online.
Prices for DIRITTO AMMISSIONE:
Le Frecce: €25 (1st/2nd class)
InterCity: €3 (1st/2nd class)
Different prices for long-distance trains towards Switzerland/Austria: e.g. €20 Chiasso – Milano (ECE/EC)
When booking, you must first select a connection via the journey planner. Then, in the ticket selection, you can choose the DIRITTO AMMISSIONE fare via the Show more offers button. You can enter the number of your FIP Coupon as the access number.

For short distances on Le Frecce, the standard fare may be cheaper than FIP reduced tickets.
Additionally, supplements for Le Frecce and other long-distance trains can sometimes be more expensive than a FIP 50 Ticket.