There are three major cell phone technologies in use in the United States. Verizon and Sprint use CDMA technology, Nextel uses iDen technology, and Cingular and T-Mobile use GSM. If you stay within the U.S. exclusively and do not anticipate using your phone outside the country, the CDMA carriers will give you better coverage and stronger signals. So if you rarely leave the U.S. coverage area, choosing one of the CDMA providers probably makes sense.

With the exception of some parts of Asia, the rest of the world uses GSM exclusively. Thus it makes sense to consider one of the GSM carriers in the U.S. Signal reception seems to work pretty well in most markets and the phone can be used in a huge internationl footprint.

One of the unique aspects of the GSM phone is the removable chip or SIM that contains information specific to the provider, such as phone number and settings. Although discouraged by most U.S. carriers by “locking” the phone to refuse to accept other SIMs, it is quite easy to obtain codes to “unlock” most of these phones.

The advantage to this design is the ability to obtain prepaid cellular service within the country where you are visiting. Especially if you will interacting a lot with the locals, having a local cell phone number makes you easy to communicate with, while roaming with your U.S. number makes it expensive for both parties. This is because the model in Europe and other parts of the world is to charge the caller for the entire cost of the call and make it free for the one recieving. But if you are traveling with a U.S. GSM phone, you will pay for the minutes at an elevated rate.

Even when it is not advantageous to obtain prepaid service on a seperate chip, it is nice to be able to use your phone for a quick check of voice mail, or to contact home. While in the Grenadines last spring, we were able to keep in touch with our businesses even from the sailboat as we came in close to islands.