Why aren't all Cell phones Compatible? There are two answers to this question. First, there are various different types of radio frequencies and encoding services which different cell phone services use - and if your phone doesn't receive the frequency and encoding of the local service, it becomes, of course, useless.

The second problem is a commercial issue - your phone will only work on other companies' services if there is a cross-billing (i.e. roaming) agreement between the mobile network suppliers. Roaming is common within the US, but becomes more problematic internationally.

To get cell phone service in another country you need both a compatible phone and a compatible account. Your best bet is to rent a cellular phone, either in the US or overseas, but be sure you get one that will be compatible internationally in the countries you plan on travelling to. There are several different ways of getting airtime as well. Read on for an explanation of all these issues and suggestions on the best way to get a phone working.

Frequency and Compatibility Issues The good news is that almost everywhere in the world (except for the US and Canada) uses GSM type digital cell phone service. This service was originally at a frequency of 900 MHz and now increasingly is being upgraded to an 1800 MHz service. If you have a GSM phone, in theory you can access service in 212 different countries! Although the US and Canada have some GSM service, most cellular phone services are of a different type and a different frequency as well!

Unfortunately, the GSM service in North America is in different frequency bands to the rest of the world - 1900 and sometimes 850 MHz instead of 1800 and 900 MHz. And there is no way that a 1900MHz phone will work at 1800 MHz (or vice versa). Frustrating, isn't it!?

Note that not all other countries use regular 900/1800 MHz GSM. Notable exceptions include Canada, Mexico, Japan, Korea, and some Central/South American countries, although there may be some limited coverage GSM networks in these countries, and/or GSM networks at the US 1900MHz frequency.