I wanted to share my experience getting a SIM card in Europe to use in my smartphone. I travel to Europe annually for a few weeks, always starting in Germany (Heidelberg/Stefan Knopf's) I use an iPhone that has been unlocked so I can install a SIM from another carrier. These comments will also apply to other phones (Android, etc) Before you leave home, download the APP called "ALDI TALK" for your phone (APP or Play Store) and install it. Easy I went to the ALDI supermarket (a huge chain all over the world), and purchased an ALDI TALK SIM card starter package. It costs EUR12.99, and includes a EUR10 credit, so cheap. You get it at the checkout counter. Easy Because I was in Germany, where they have rules regarding cell phone registration, the activation and registration process gets messy. Using the ALDI TALK App, which is in Germany (!) enter the information for your SIM that comes on the cardboard id card included in the starter package. There is a SIM number, your new phone number, and several PIN and PUK (unlock) codes on the card. Not so Easy, used google translate to read all the mumbo-jumbo. You can punch out the size SIM you need from the id card (SIM, Micro, Nano). With the SIM installed in your phone, you now need to Register yourself. You will need an address in Germany, any address thats real, but they will not check to see if you live there. This requires your passport and a strong WIFI internet connection. You will be going online to an ALDI website and will enter some identifying info and then you will initiate a video connection to ALDI's agent (English speaking requestable). The agent will direct you to hold up you passport to the smartphone camera and will capture your id. Amazingly, this works. I was standing in my hotel bathroom with a strong light source. Not too horrible Once the registration is complete, you wait for 24-48 hours for your SIM to start working. You will receive an email (German) saying it's working. Until then you get NO SERVICE on phone. Magically it all works. You now have a EUR10 credit on your account and can talk, text and even do some internet. I then added a BIG 5.5 GB data flat rate package to my account for EUR14.99. To do that you can buy credit at ALDI, or get E-Plus credit at many outlets in Europe. You cannot use your non-German credit card. So, after two days, I now have internet access so I can use google maps and call hotels and get in touch with whoever I need if the bike breaks, etc. All this is good for one month. Note: All of this is much easier if you have a patient, German speaking friend nearby. I did not, so I spent an hour or two in my hotel one evening...... Alternative is to go into a major player phone company shop (O2, Vodaphone, etc) and pay a bit more for their flat rate prepaid package, some will help you, some will say NO. Another alternative is to go into any of those immigrant focused little phone shops and tell them to set you up with a SIM. They mostly use one of the phone reseller companies (MVNO's). They will make it happen. Not sure about the legality. All of these options are better than using your USA based carriers international plans. Mine was ATT and their Passport Plan is pretty expensive for very little data. I hear T-Mobile is better. Good luck.