Roaming adjustments are abroad for calls not needed Your Phone works also on prepaid automatically. 

Hi Friesian,

thanks for your feedback , so this means that I just need to top up my balance and my prepaid SIM will work automatically ? 

For as far as I know is roaming adjustments needed for the use of data. Yes enough prepaid amount is needed. This page has a lot of info for you although it is in dutch.

https://www.kpn.com/prepaid/buitenland.htm

Make sure that you know the zones and Costs for example maritime and satelite also.

*Edit*

@Gohar 

Be aware that your amount is usable abroad in zone 1 countries. Other zones are very expensive.