Some tips from my recent experience may help people who want to buy Austrian and German top ups using
https://www.onlineaufladen.at/ before they arrive. I have an A1 B.free prepaid SIM from a previous trip to AT. That SIM lasts 365 days and I wanted to top it up before it expired so I could use my phone the moment I arrived in AT.
1. If you use a Visa card it must be registered for the Verified by Visa program. The first Visa card I used isn't and the issuer, Chase Canada, has no plans to join VbV. I don't qualify for the other payment options which seem oriented to people in Europe.
2. Even if the card is VbV the payment processor apparently uses IP geolocation to reject transactions from overseas.
3. I then wasted a lot of time contacting onlineaufladen.at, the bank that issued my VbV Visa card, Visa, etc.
4. Then it occurred to me that I could circumvent 2. by using a free proxy or VPN service like
https://www.tunnelbear.com/. I set my country to Germany and then had no problems buying a top up for A1 B.free.
It seems silly to block overseas transactions using IP geolocation when it's so easy to circumvent the block. It's even sillier to do this for small transactions like EUR20.
Hope this helps someone...