GSM status quo
Someone on a mailing list recently asked an innocent question about the jigsaw puzzle that is GSM in the United States. Since I haven’t yet found an up-to-date synopsis of the subject, here’s a few notes for your perusal, dear readers.
When one hears GSM, what is usually meant is GSM 900, which is the frequency most commonly used in EMEA (Europe, Middle East, and Asia). The problem for consumers is that GSM 800 offers better coverage in the US, as GSM networks here have primarily grown out of existing AMPS networks that used the same frequency band.
In the Bay Area, at least, GSM 1900 coverage is poor and is bound to get worse as the AT&T/Cingular merger continues — those two companies are investing heavily in GSM 800. AT&T has been building out their GSM 800 network for some time now and Cingular will be switching over to that frequency where possible once the merger is complete, see here. GSM 1900 doesn’t penetrate buildings as well as GSM 800, which explains Cingular’s eagerness to switch (and why Verizon’s coverage is better than Sprint’s, incidentally).
When people buy a phone in the US for international roaming, they usually get one of two things: a GSM 900/1800/1900 phone that they can use on 1900 in the US and 900 elsewhere, or a GSM 800/900/1800/1900 phone. The latter is preferable for coverage in the US, but the trend is for phone manufacturers to offer US and non-US SKUs where the only difference is GSM 800 vs. 900.
And in case you were wondering, GSM 800 and GSM 850 are different names for the same thing.