Question about Galaxus Mobile Basic plan

Hi, I have bought the Basic plan. When I go on holiday to Austria and Hungary, do I have to buy a data pack? I always had problems with Swisscom, even though I bought a data pack. As soon as I crossed the border, there was "no network" and so I couldn't log into the Cockpit. No SMS, nothing. How should I proceed? Thank you for any information. My plan will be activated tomorrow.