You no longer pay roaming charges for your mobile usage in the EU zone. So when you call, text or browse via mobile internet from an EU country, you pay the same as you enjoy in Belgium.
When you text, browse or call from a country outside Europe, Switzerland, Monaco, Andorra and Jersey? You will still pay the international tariffs, in addition to your monthly amount.
Good to know: Switzerland, Monaco, Andorra and Jersey are not part of the EU zone.