Your Galaxus Mobile CH Unlimited plan includes a monthly 1 GB of roaming in the EU/USA (zone 1). The Galaxus Mobile Basic plan doesn’t include roaming.
You can keep a check on your roaming costs whenever and wherever by logging into your Cockpit.
If you want to add more data packs for abroad, you can also easily do so in the Cockpit. Under «Usage», select «Add data pack».
You’ll find tips on how to avoid getting hit with high data roaming charges in this article.