To find out if you need a ticket, I suggest you call us at 0848 44 66 88 (CHF 0.08/min) or +41 51 225 78 00 (from abroad). You can also go to any SBB counter in Switzerland. Here you will find our opening hours.
You can also check on SBB.ch. All you have to do is search for your connection and enter the subscriptions you have in the passenger’s details.