The International plan offers unlimited data in the EU/USA (20 GB full speed) and 100 minutes of calls to the EU/USA per month. Unlimited calls within the EU are not included - the exact costs for additional calls are not specified in the information provided. For details on international calls outside the inclusive quota, we recommend contacting Galaxus Mobile directly.
Note: The in-house product data does not contain any information on international calls, so this answer is based on the official Galaxus resources.