I've used the A-1 B-Free SIM for several years, as I make twice-yearly trips to Vienna. There is an A-1 location downtown on Kartnerstrasse. I haven't checked at the airport because I've had the card for quite a while. As far as I know, it never expires, because I can leave in June, go back in February, and it still works with whatever Euros I still had on it when I left.

They have the capability to do instructions and voicemail either in English or German, which is great. You can buy recharge vouchers all over the place at any tobacco store. I haven't tried to set up a credit card account because you need an in-country address. Recharge vouchers are so easy to get as well.

If you search on line, you can find instructions in English you can download as a PDF.

The main reason I go this route is because it's the cheapest way to call home. Don't EVER sign up for international roaming unless an employer is paying for it! The cost is enormous.

I haven't looked upstream to see if anyone else has mentioned this, but, make sure you have an unlocked quad-frequency GSM phone. AT&T and T-Mobile use GSM in the U.S. Verizon and Sprint do not, so, their phones won't work.