What is the best solution for smartphone SIM card for traveling in Europe with roaming charges?

I'm assuming that your smartphone is locked to your current carrier. Locking prevents your phone from working with any carrier but the original one you bought it from. If you're curious, check out the Wikipedia article on SIM locking (1). From here, this answer goes in two directions. You can either:
  1. Keep your phone number (which will take less work, more money), or
  2. Get a new phone number (more work, less money)

Keeping your number
Whatever you do, don't just jet off to Europe and start using your phone. Set yourself up in advance with some sort of roaming plan. Lifehacker (2) and Engadget (3) have covered the subject pretty well, so I won't bore you by regurgitating everything they've said. The takeaway from both of them is the following:
  • If you're not on AT&T or T-Mobile, you're probably out of luck. Verizon, Sprint, and other CDMA carriers won't even get a signal in Europe (unless you're using a special "worldphone" and you'd probably know it if you were).
  • Be prepared to pay unfathomably high prices. AT&T offers a roaming data plan for $25 per month and that gives you 50 megabytes (for perspective, this is 40 times as expensive per megabyte as the local rate). At the high end you can pay $200 for 800MB of data (that's still the equivalent of 20 times the going rate back home) (4).
  • Seriously, find another option. Don't make your bank account sad.

Getting a new phone number
In the UK (in London in particular), you'll probably spot tons of small "hole in the wall" cell phone accessory shops all offering to unlock your phone for something like £20-30GBP (that's about $47USD at the moment). Despite the really sketchy appearance of the storefront, they're actually quite legitimate. The process took me about 15 minutes and they even sold me a prepaid SIM card to start me off. As an aside, don't lose your home SIM card; you'll need it when you get back.

If you're going to be using any data at all, a local SIM card will suit you best. You can buy a prepaid SIM card with £15 of value on it and the carrier will generally give you some bonus of free data (Virgin offers 1GB plus unlimited texts if you "top up" with £15) (5).

So in conclusion:
  • Get your phone unlocked before you leave if your carrier will do it for you, then buy prepaid SIM cards as you travel.
  • Alternatively, get it unlocked when you get to Europe, then buy prepaid SIM cards.
  • If that's all too scary for you (or if it's absolutely vital that you keep your local contact number wherever you travel), call up your carrier and tell them you'd like to add an international roaming plan to your service. It's steep, but not as steep as just showing up and using it.

Hopefully this isn't too daunting an answer. If I've left anything ambiguous or vague, feel free to ask for more info. And the links below aren't required reading, per se. They just might be interesting if you're curious and/or bored :)

1 - SIM Locking: http://en.wikipedia.org/wiki/SIM...
2 - Lifehacker: http://lifehacker.com/roaming-ch...
3 - Engadget: http://www.engadget.com/2010/06/...
4 - AT&T's "super affordable" (their words, not mine) International Data Plans: http://www.wireless.att.com/lear...
5 - Virgin Mobile's prepaid offering: http://www.virginmobile.com/vm/p...
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DOODAD International SIM Card for Data Roaming

Travel Safe!
As well as Ali assumes  your phone is locked to your current carrier, we must also assume we are talking about a GSM phone, those are the  ones that use SIM cards or SIM chips.

There is another technology of cell phones,  CDMA,  which, may be also locked to your current operator but you wont be, as easily,  able to change the sim chip, nor the number assigned to that phone. 

So, We should stick with the GSM technology phones for this exercise.

Now; Which countries you will be traveling to ?:

I have found that purchasing a local SIM chip on each country I visit is the best option.  The factor of "how long are you be staying in each country" is another issue. If you are staying for one or two days, it may not be worh the time to go and buy the SIM chip.   For longer stays, a visit to a local cell phone or cellular service shop may be worth the time and the money.  You have to make your sums on how much the sim chip card costs, how much credit you get in that sim to make calls (local or international) or send SMS (which is the most useful thing, for me at least) and decide if it is a good treat or not.

Also what Ali refers above as "getting a new phone number", I would better express is as "getting an unlocked cellular phone".  Why is that?  Just because with an  unlocked cellular phone, you can still use your home sim chip (thus you are not changing phone number!)  or,  you can use any of the "local" sim chips you may purchase as I explain above.

Carry two cellular phones with you.  I always have two phone devices (in my case, both happen to be SIM unlocked, by the way)... The one where you will insert  the foreign SIM chip, must, I repeat must, be SIM-unlocked or "unlocked" for short. If it is not unlocked, it won't work with the foreign sim chip. 

This way you can always have your local home phone number operating in one phone "in Roaming mode, of course",  you can get calls (but NOT answer them)  a lot of times you get the calling number on the screen (not always tough)... so you can at that moment with the other phone or whenever you consider convenient return the call through the most appropriate way (the pther phone with the local sim, VoIP, Skype, etc).  You can also get SMS from home phones/contacts and those are not THAT expensive.  I dont like to totally loose connection or contact with home.

On the second unlocked cellular phone number, you will be inserting the local sim chip with the local number. This is the one that you will be using to communicate locally, (i.e local numbers, with your travel peers if the happen to have their own local numbers, etc.) or to place international phone calls...

Bear in mind in any case, that there are different frequencies for different cellular phone systems. Most modern cell phones are quad-band or penta-band, meaning that it is most probable that it will work fine in your destination(s). 

Also, one thing is voice communication, which relies on the GSM standard (and also provides low speed data services called EDGE) and another game is the 3G/4G data services. You have to check for the frequencies for 3G/4G data services in your destination(s) if you plan on using that as well with the local sim chip.

Last, but not least, here are some useful links:
This site is very handy to get to know the local prepaid cell service offers on a per country basis:


Here in GSMARENA you can check, in a friendly way, on the most common used frequency bands for voice and data for several countries. Select your country of interest and read the table. Make sure your phone operates on the indicated frequencies for "that" country.


Hope this information is useful. Happy travels.

Best solution is buy international sim card you will get free roaming and unlimited data plans depend choose plans.

if you're travelling to Europe then buy Europe international sim card.

Upon my experience travelling I found a data roaming service provider that provides good service at the same time challenging the norm.

You don't need to change simcard with your existing one. Keep your current carrier and install Flexiroam.

Just attach the ultra-thin microchip to your SIM and enjoy data roaming in over 100 countries!

With the microchip attached to your SIM, you can connect to the internet whenever and wherever you travel! Just stick it on your existing SIM once and you'll be able to use it every time you travel.

Your best option would be to setup a prepaid service with TMobile, either under the One plan $50/mth with global roaming in many countries for free (talk, text and data), or go with their tablet data plan. Again it roams in many countries for free and a 5gb package costs only $10 USD and can last you up to 150 days in total. If you run out of data, you can easily add more data to your plan online through their website. This last option works really well on an unlocked data enabled tablet, like the TMobile AXS Trio 4G, an unlocked Samsung Note 8.0 LTE, an unlocked wifi hotspot, or you can even set it up on a cell phone.

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