Global cell phone guide
I travel a lot, and since I do not want to pay high international roaming charges, I always buy SIM card on the location and use it. Now you can do it, too, provided your cell phone is up to the task.
First, you have to make sure your cell phone is unlocked, which means it is not tied to a certain network. Many cell phones are locked whether you know it or not (unless the seller specifically says it’s unlocked, chances are it’s locked). Even if it is locked, many phones can be unlocked through some kind of hacking. Sometimes it can be done through special software. Or you may have to send it to a shop which can unlock it for you. In any case, you will need to do some research on your cell phone.
Second, your cell phone needs to be tri-band or quadri-band. The US cell phone networks use 850 MHz and 1900 MHz. In other parts of the world, 900 MHz and 1800 MHz are used. So, your cell phone needs to have at least 900, 1800, 1900 MHz (tri-band) to be usable in different countries. Quad-band (850, 900, 1800, 1900 MHz) looks better on the paper, but tri-band seems to be enough in most of the case.
Now there are two more factors to consider. First, GSM vs CDMA. GSM is de facto international standard of cell phone. CDMA is used in certain Asian countries (like South Korea), and by Verizon in the US. So, if your cell phone is CDMA, it will be quite useless in most part of the world.
Second, most cell phone companies are introducing W-CDMA, which is 3G standard. So, it is highly possible that the country you are visiting has both GSM and W-CDMA networks. If you have GSM tri- or quad-band cell phone, it should work fine. I don’t think GSM network will disappear anytime soon. But eventually they will, and then you will need to get a 3G tri- or quad-band cell phone. Some phones have both GSM and 3G (since 3G network is not complete, it connect to the network through GSM when 3G network is not available).
In conclusion, just buy a unlocked tri-band phone, and you will be able to use it anywhere in the world (that is, except for South Korea). I bought a Motorola RAZR V3, and I used it in the US, Germany, Brazil, and Australia.
Just to give you an idea, I found a web page with list of international cell phones.
