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There are now more choices for how you place cell phone calls while traveling.

And competition has driven down calling costs, with some of the new products offering very affordable rates.

But other options remain very expensive.  Choose your preferred method of keeping in touch while traveling with care.

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Which is the Best International SIM?

How to choose the best SIM and phone service option for your phone when traveling internationally

Choose whichever of seven different types of SIM card and its associated phone service works best for you on your travels and simply swap it (them) in and out of your GSM phone as you travel from home to other countries.

Part 9 of an 10 part series - click for Parts One  Two  Three  Four  Five  Six  Seven  Eight  Nine  Ten



It is important to choose the right SIM and service for your phone when traveling internationally.  A wrong choice at best may cost you a great deal more money for the calls you make and receive, and at worst, may mean that you have limited or even no service at all while away from your home country.

This information will help you understand the issues offered by various different SIM providers and make the best choice for your situation and circumstance.

Other articles in this series about international cell phone service are also helpful.


Introduction - SIMs and Service

With a GSM type phone (see Step One below) your phone itself has no 'identity' or associated phone number.  All this is kept within the user swappable SIM card that you plug into the phone.  You change your SIM and this changes your phone's service provider and phone number.  Think of a SIM as a regular telephone line, and your cell phone as a regular phone - a regular phone can work on any telephone line, and assumes the number associated with the phone line.  The same concept applies (more or less) to GSM type cellphones and the SIMs they connect through.

This flexibility works greatly to your advantage when traveling outside your home wireless provider's network.  No longer do you need to suffer very high international phone call costs, instead you can mix and match SIMs and their associated services and costs as you travel from country to country so as to get the best value phone service.

Step One - Confirm your phone works internationally

Before you start to consider different SIM and service options for traveling out of your home country, you first need to confirm the phone you plan to use will work in the countries you plan to visit.

Most countries use GSM type phone service, and there are four different frequency bands variously used by different countries.  Here is information about which countries use which GSM frequency bands so you can make sure your GSM phone has the necessary bands to work in the countries you visit.

In the US, the two main GSM based phone companies are AT&T/Cingular and T-mobile.

Some phones use a different type of service such as CDMA (this is used by Sprint and Verizon in the US, for example).  Not many other countries have CDMA based cell phone service, and if you're traveling outside North America, you will need to buy an unlocked GSM phone to use on your travels.  We sell some ourselves, and another reputable supplier of unlocked GSM phones is Telestial.

Step Two - Confirm your GSM phone is unlocked

If you acquired your phone when signing a contract for phone service with your wireless provider, the chances are it is probably 'locked' and will only work with the SIM your current wireless provider gave you.

If you want to use a different SIM in a locked phone, the phone will need to be electronically unlocked before it will accept a different SIM.

How to tell if your phone is locked or not

The easiest way to tell is to put a SIM from a different wireless service in the phone.  For example, if you have a Cingular phone, try putting in an older AT&T SIM or a T-Mobile SIM (or of course any other SIM from any other wireless company, anywhere in the world).  Chances are someone else at work has a phone with a different SIM that you could borrow for the quick minute this takes.

If the phone is locked, it will display an error message of some type when you turn it on with the other SIM installed (typical messages include 'Contact Service Provider' or 'Enter Subsidy Code' or 'Invalid SIM').

If the phone is unlocked, it will either start up normally, or perhaps will start up and then say 'Unregistered SIM' or 'No Service' (if using a foreign or old SIM).

How to unlock a locked GSM phone

The first thing to do is to ask your current wireless provider if they'll unlock your phone for you, for free.  T-mobile will generally do this if your account is in good standing and you've been a subscriber for more than three months.  AT&T/Cingular is unpredictable - sometimes they'll unlock your phone, but often they won't.  Their current (Nov 07) policy seems to be that they'll unlock your phone once your one or two year contract has been completed.

If your cell phone company refuses to unlock your phone, don't panic.  Many companies offer unlocking services, including, ahem, ourselves.  You'll see links in the 'Related Articles' box on the top right of this article to pages about unlocking various different brands of cell phone.

Step Three - International Charger or Adapter

Now that you have a phone that you've confirmed will work in the countries you're visiting, and unlocked to accept whatever SIMs you choose to use, there's one more thing just to quickly confirm before moving on to the issue of which SIM or SIMs you should get.

Is your charger multi-voltage

Just make sure your phone charger is multi-voltage so that it will work with the voltage of the countries you are visiting.  North America uses 110V, most other countries use somewhere between 220V and 250V.  Most - but not all - phone chargers these days are multi-voltage, but quickly read the label to confirm it says something like 100V-250V or maybe 110V/220V to indicate it is multi-voltage.

If the charger is not multi-voltage and you're going to a country with different voltage to your home country, you'll need to either get a multi-voltage charger or a transformer to change the voltage you feed into the charger.  The better choice is just to get a second multi-voltage charger - they are not very expensive and are very convenient.  This company has a wide range of chargers at low prices.

Plug adapters

If you're traveling to a country with different voltage (and even if you're not), the chances are that it might use a different type of plug to fit into the wall sockets.  Get a set of plug adapters from a local electronics store (such as Radio Shack in the US).  These are lightweight and inexpensive.

Bad News :  There's No Such Thing as a Single Best Solution for International Phone Service

If there was a single best solution for everyone's needs while they travel internationally, this article would be very much shorter and simpler!

But this is not the case, and so you need to balance the different factors that make up how you'll be using your phone internationally to find which of the many different approaches is the best compromise between cost and convenience.

A person who travels very regularly and uses their phone extensively would probably end up choosing to buy individual prepaid SIMs for each country they regularly visit; a person who makes only occasional journeys and expects to use their phone very seldom would probably choose a Mobal SIM or to simply use international roaming with their home service provider.

If you fall somewhere between these two extremes, or if you have special needs, then read on, and review the summary table and the explanatory notes that follow.

Your Service Choices

We've compared ten different service options for your international phone service.  Here's a quick summary of the strengths and weaknesses of each option.

Here's a quick summary of the strengths and weaknesses of each option. (This will pop up in a new window.)

The next table lists detailed features and rates for each of the ten different options, so you can better understand the strengths and weaknesses of each option and how it would relate to your own usage.

Detailed feature and rate analysis for each option (This will pop up in a new window.)


Traveling with a cell phone is getting easier and more affordable.  No longer do you need to pay many dollars a minute to send and receive calls - the latest international SIMs and their associated calling plans will often give you unlimited free incoming calls, and outbound calls for between 50 and $1 per minute.

Use the two tables above to match your own travel and phone usage patterns to the best SIM and service option.

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Originally published 19 Jan 2007, last update 21 Jul 2020

You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.

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