The Cell Phone Thing, Part III: SIM Cards

Looking to use a cellphone overseas? I’ve explained how your Verizon phone may work in a very few countries, and how certain kinds of T-Mobile or Cingular/AT&T phones may work in much of the rest of the world. But if that doesn’t help you, there is another way: SIM cards.

First, to recap. If you’re traveling in North America or some parts of the Caribbean or South America, you may be able to use your Verizon phone. If you are traveling in Europe or most of the rest of the world and you have a T-Mobile or Cingular/AT&T tri-band or quad-band phone, you can probably roam on that phone.

Cellphone Series

I: Verizon
III: Using A SIM Card
IV: Finding A SIM Card
V: Calling Plans
VI: Tips & Miscellany

Still, that leaves many of us out. As I explained, most people who have T-Mobile or Cingular / AT&T phones have the right technology (called GSM) but the wrong frequencies for overseas. Dual-band cellphones in the United States work on two frequencies that aren’t used in Europe or most of the rest of the world. So, only a tri-band or, better yet, quad-band GSM phone will work. (Unless you have a dual-band phone that works in Europe but not the U.S. … don’t worry, I’m getting there.)

Actually, it can get a bit more complicated. I mentioned that my T-Mobile account is prepaid, so I’m not permitted to roam overseas, even though my phone is technologically capable of doing it.

Still, I used my quad-band phone in Russia, easily and cheaply. Here’s how:

In Russia, I bought (or rather my Russian-speaking niece bought) a prepaid SIM card for about $6. This card was actually a tiny chip that I inserted in my phone. It assigned my phone a local Russian phone number and it came with 150 minutes of airtime that I used primarily to talk to and text message my niece, who had a Russian phone, and my sister, who was also visiting Russia and had bought a chip for her dual-band European-style phone.

When I got home I threw out the Russian chip and put the T-Mobile chip back in my phone. I got my U.S. number back as if nothing had happened.

Even if you have a quad-band phone that can roam overseas under your carrier’s plan, you might prefer to use the chip. The local rates are much cheaper than roaming.

Now, here’s a very important point. In order for another SIM card to work, your phone must be unlocked. If your phone is locked, only your carrier’s SIM will work.   And that’s how carriers sell their phones. Locked.

I bought my own phone, unlocked, over the Internet, then bought a SIM from T-Mobile. Had I bought the phone from T-Mobile, however, the company would have unlocked it for me after 90 days of use. Cingular / AT&T has a reputation for being less accommodating, but knowledgeable technophone types can unlock phones for you. PC World’s website has a very understandable explanation of this.

But maybe you don’t have a quad-band phone, locked or unlocked. What then?

You might consider buying an inexpensive, unlocked dual-band GSM phone that has the two European bands that work in most of the world. A colleague who often travels to Italy told me he did just that. If you buy a GSM phone to use abroad, you can just insert local SIMs for any country you visit. 

There’s a great article on how to do all this on

There’s some very detailed information on how it all works on The Travel Insider.

Let’s suppose you do have an unlocked phone you can use abroad. Where do you get the SIM? How do you start? We’ll get to that next.


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