@ eberg
Don't think about roaming with an austrian SIM. Go for yesss! (sold in HOFER (Aldi)) supermarkets everywhere. The SIM (Prepaid = Wertkarte) comes with at least 1GB and is ready to use without registration. It is possible and easy to register on
yesss! to easyly administrate and check all details.
Top up is easy with vouchers (20€ for 2 GB/1 year validity) also from HOFER shops and many others.
You can also buy a A1 starter set for 20€ which comes with 1,5GB. Recharge is also 20€/1 year but only for 1,5GB.
I have been using both cards all over Austria and the Yesss is really not bad.