One way or another you need an active membership to be able to use services while abroad.
However membership allowances do not work.
If you are in the EU then you can buy EU roaming add-ons to get certain allowances - see here:
If you don't do that then all outoing and incoming calls and outgoing texts must be paid for from your cash credit balance. The charges that apply are also available from the link above.
Data does not work abroad so you will have to use wifi where available for internet access.
You seem to be using an iPhone? If so then this tip is also worth knowing about in case you have problems when trying to connect abroad:
Hope this helps.