The GSM Unlocked Cell Phone

GSM is implemented on different frequencies across the planet. Your international destination(s) will determine which frequencies you will need. In summary:

Europe, Asia and Africa including the South Pacific operate on the 900Mhz and 1800Mhz frequencies.
North America and Central America operate on the 850Mhz and 1900Mhz frequency.
South America and The Caribbean may use the 900Mhz, 1800Mhz and/or the 1900Mhz frequencies.
Some phones switch between bands automatically while others must be set manually (this is no big deal). The Motorola Timeport demonstrates a manualband selection. The 2 options are GSM 900/1800 (for your trip to London) or GSM 1900 (for when you return to North America).
The GSM Unlocked Cell Phone