nwhitfield
Member

Registered: Feb 2000
Location: London, UK
Posts: 92 |
In theory, GSM should be the same everywhere; however, most of the world uses a mix of two frequencies 900MHz (the original GSM standard) and 1800MHz. Older phones tended to work on only one band, but most modern GSM phones are both 900 and 1800MHz, with transparent switching between the two. Some networks use both, others are one band only; typically older networks use GSM900 and newer ones, or those in densely populated areas prefer GSM1800.
For various reasons (chiefly availability of spectrum), when the US started building GSM networks, they chose a new frequency of 1900MHz (and some newer US ones may be using yet another unique band too).
When people talk of a World Phone in GSM terms, they usually mean one that has both 1900MHz for use in North America, and 900MHz to use elsewhere - few places have only an 1800MHz network.
Some phones can work on all three currently deployed frequencies 900/1800/1900, but they're mostly Motorolas, so don't count. Ericsson has a few as well, like the luscious T68i.
VisorPhone works on the 900 and 1900MHz bands, so can be used anywhere where there is coverage on either of those. (Treo, incidentally, is available in two versions; for North America 900/1900 and for everywhere else 900/1800).
In Guam, the sole network is operated by Guam Wireless Co LLC, and uses the 1900MHz band, so VP will be fine there.
The best place to check this information is www.gsmworld.com, where you can find a list of networks by country in the GSM Roaming section. Click on a network's name to see details including coverage maps and the frequency used.
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