Any advice on buying a SIM card on line for my unlocked phone? I will be mostly in UK but also Greece and Turkey. I would like to get one before I leave so I can give out the number. Cheap but reliable. Don't plan to use it much. Please advise.
T Mobile has a data only plan for Pads (not phone). You get a sim and pay monthly (no contract). Europe there is no need for 4G. 1g to 3g should be plenty. The fee is $10 up (depending on the g). You can cancel anytime.
Verizon is having an international plan promo. For $25 you get 100mb per month of data (not calls or text). It is essentially a roaming fee. There's no need for a new sim card if you are a Verizon customer. It's also no long term contractual requirement. You can buy a month and cancel before the next pay cycle starts. When you are out of the country, when connected with wifi (say, from hotel or cafe), the data is not part of the 100mb. Unless you stream movies, 100mb should be plenty. The next level is $200mb for $50. To call and text, I use Whisso app that converts phone numbers via data streaming. The ones you call and text doesn't have to have an account (like Skype or Whatsapp). To them it's a normal looking incoming call or text.
I don't know what plan AT&T offer.
You can always buy a sim from local phone carriers while you are in their country. Just make sure what comes with activating it. In italy, the sim must be registered with ID (passport) and you may be issued a phone number. All the fees and added costs may set you back $30 to $50 (US dollars) for a month of using. You should google about UK sim card for unlocked phone situation.
The “travel” SIM cards you can purchase in the USA are terribly expensive. The voice, SMS and data rates will make your eyes water! My best advice is to get a local SIM for your phone once you get there and then just text out the number to those you want to have it.
I used O2 when I was in London last fall. The great thing about using a U.K. company is you can readily understand the web site (once you get over the American to English language barrier).
I had no need to evaluate O2’s continental roaming costs but you may be able to get away with purchasing just one SIM for the entire trip.
From above "Europe there is no need for 4G. 1g to 3g should be plenty." I completely and whole-heartedly disagree with this statement. If you are using a smartphone as an internet device (web searches, directions, etc.), 1G and 2G is much too slow and 3G is marginal unless you are in a very well serviced area.
By the way, the T-Mobil (USA) no-roaming plan limits you to 1G speeds when accessing the net overseas. Not worth it...
I would absolutely wait until you get to the UK to get a SIM card if you can. It will be much easier and cheaper than doing it in the States by far.
You might want to poke around eBay for people selling local SIM cards. I picked up a couple of SIMs for Three in the UK for my kids on a recent trip. Three has pay as you go unlimited data top up for £20 for the UK that also gives 25GB roaming in about 15 different countries. It worked great for us. I don't know that Greece or Turkey is covered by the roaming plan.