SIM Card City

In my last post I discussed different methods for staying in touch while traveling, ending up with purchasing a "world phone" (an unlocked GSM capable cell phone) and purchasing SIM cards. As I wrote then:

Unlike standard US cell phones which are tied to a single provider's network, with GSM phones, much of the important logic governing who your service provider is and what number your phone is attached to is stored on a removable card, called a SIM card, in the phone.  If your phone is "unlocked" then you are able to freely change the SIM card at any time.

This means that changing phone plans is as easy as swapping in a different card.  Since unlocked GSM phones can cost as little as $20 or $30 and the same for a pre-paid SIM card, this gives you a lot of flexibility.  But it leaves you with a decision — what's the best card, or combination of cards, to use for overseas travel.

Let's examine the question of which card to use.

Local SIM Cards

As you move from country to country you can buy a new SIM card so that your phone number and provider will be within that country.  You will then get local rates for calls within that country, and you will have the same international calling rates and roaming privileges that someone with service in that country has.

In general, when you purchase a SIM card, it will have a usage credit included.  You might pay $20 for the card and receive (along with a new phone number) $10 worth of calling credit.  You can then add credit to your card any time you want.

For instance, if you're traveling to France and Italy you would, on arrival, purchase a French SIM card and install it in your phone.  You now have a French mobile telephone number and can call within France like a local.  Calls overseas will be charged at the international rate that is associated with the plan on the SIM card you bought.  

When you travel to Italy, you can continue using your French cell phone, paying whatever international roaming charges are associated with your plan (because your phone will now need to use an Italian service provider).  Alternatively, you could remove your French SIM card (saving it if it still has credit on it, or you want to preserve the phone number) and buy an Italian SIM card.  You get a new (Italian) phone number and local calling within Italy.

What are the rates?  For country-specific SIM cards in Europe I've seen them as low as about 22 US cents per minute for both in-country and international calling, depending on the country.  Other countries are variable — service is much more expensive in Mexico, for instance.

The advantages of using local SIM cards are that you have the best price calling within the country where you purchase the SIM card.  You also have an in-country number to give to friends or family in that country.   This works well if you're planning to be mainly in one country.  If you're traveling around a good deal, however, you'll find yourself switching phone numbers frequently and if you want others to be able to reach you you'll need to let them know every time your number changes.

International SIM Card

A number of companies now offer international roaming SIM cards.  These are SIM cards in which you receive a permanent phone number in one country (it generally seems to be Britain) and a service plan that is usable in any GSM country in which the phone works.  The rates are not as cheap as local calling, generally starting around 50 US cents per minute and heading upwards from there.  For that higher cost, however, you get the ability to use the phone in any country without replacing the SIM card and you keep one phone number as you travel.

One thing to watch out for with international cards is to make sure that incoming calls remain free in those countries where this is normally true.  (Free incoming calls aren't really free, by the way, it's just that the caller is charged the per-minute cell phone surcharge.)  Sometimes it's worth it — Telestial has a card that charges for incoming cell phone calls even in Europe, but in exchange their rates for both outgoing and incoming calls are not much different from having a local card.

Some international SIM cards are prepaid, meaning you get a certain amount of credit to start and then "recharge" your account in pre-determined increments.  But some offer credit card billing in which you pay only for the minutes you actually use.  That's more efficient in those cases where you won't be talking a lot (or may not even use the phone at all), although the per-minute charges with these services are generally higher than with prepaid services.  Mobal offers this kind of service and advertises in a lot of in-flight magazines.  They offer post-billing (you only pay for the calls you make) and a permanent number (it doesn't expire after 9 or 12 months).  In return, their rates are high— $1.25 per minute and up for calling from Europe, for instance.

Mix & Match

If you have an unlocked GSM phone you can mix and match local cards and international cards as desired.  For normal travel you can use your international card, but if you settle for a while in a single country you can temporarily swap in a local card.  Although I don't yet have a phone, it looks like I'll be getting a cheap unlocked GSM phone and the cheapest international roaming card I can find.  If, in the future, I wind up spending a lot of time in one country, I'll just pick up a local card there.