I notice a lot of confusion in these forums and others about SIM cards - the fact the number changes, sometimes you need different SIM cards for different countries, where to acquire them etc etc.
I'd like to suggest an alternative method I have been using, which is cheap and simple. Use Skype with wifi, and keep your United States SIM card with the cell service turned off. This is how:
- Download the skype app on your smartphone
- Set up a skype account. Put about $10 credit in the account. Now you can call land lines in the US and abroad. $10 lasted me about 2.5 months in a 3 month trip last year. I think its a few cents per minute to land lines, and - amazingly - they don't charge you for calling 1800 numbers.
- If you want people to be able to call you, get a skype number - would cost $18 for three months*. Now people can call you from any landline or cell in the world. You also get free voicemail (but no SMS capability).
The above steps will take about 10 minutes. Now, when you are in europe (or anywhere), turn off your data and cellular, go to wifi only. Anywhere you are is likely to have WiFi these days - hotel, airport, restaurants, cafes etc - in fact some entire downtowns now are covered in free wireless networks
If you have a true emergency, and absolutely need to use your phone right this second, and you happen to not be in a wifi zone, you can turn back on the cell and spend the few $ a minute to call
To me the pros of this approach are the low cost, the lack of having to mess around with multiple numbers, sim cards etc. Call quality always seemed good. I think there was only one time I really needed wifi and couldn't get it. The cons are you are not 100% connected at all times (if you can call that a con) but that's what voicemail is for. I used this on a recent 3 month, 17 country trip through the Middle East, Balkans, Eastern and Central Europe and had no problems.