If you want to use your existing cell phone while traveling, it must be compatible with the wireless format
(e.g., GSM, CDMA, etc.) and the frequency (850 MHz, 900 MHz, 1800 MHz, 1900 MHz)
used in your destination country.
Determine if your phone will work in the country you are traveling to. If it is a dual-band, tri-band, or quad-band phone, it MAY work when you travel.
You can also buy a multi-band phone that will work here and in your destination country.
GSM Service - (Global System for Mobile communications)
GSM cellular technology is used in over 220 countries, including the U.S. The frequency used, (850 MHz, 900 MHz, 1800 MHz, and 1900 MHz) varies from country to country.
Click here to see which U.S. carriers use GSM and the frequencies used.
Most phones do not support the frequency bands needed for international travel, and they cannot be modified to make them work.
Check with your current cellular carrier if you are unsure whether your phone supports the band used in your destination country.
CDMA Service is also used in the U.S. and other countries, but less common than GSM.
Click here to see if CDMA is used in your destination country and to discover
which U.S. carriers use CDMA and the frequencies used.