GSM & CDMA

• These appealing acronyms stand for: Code-Division Multiple Access vs. Global System for Mobile Communications. Did You Know: CDMA technology was used to thwart German communications jamming during WW2. Good trivia for cocktail party chatter.
• For the North American consumer, this essentially boils down to Cingular/T-Mobile (GSM) vs. Sprint/Nextel/Verizon/Alltel (CDMA) For non-U.S. customers, GSM is more or less universal.
• GSM takes a SIM card; CDMA is tied to the phone. This doesn't really matter all that much, the "user experience," as they say, is essentially the same – unless you travel overseas. GSM is the de facto standard in Asia and Europe. Your CDMA phone will be all but useless. At any rate, if travel overseas is not an issue, it doesn’t matter.

Frequencies

• With CDMA, it doesn’t really matter. You didn't ask, but I'm telling you anyway: CDMA does not assign specific frequencies -- instead, every channel uses the full available spectrum, and transmissions are encoded with a pseudo-random digital sequence.
• With GSM, you want to look for 850MHz and 1900MHz frequencies in the U.S.; 900 and 1800MHz overseas.
• In North America, 850MHz is prevalent in remote or rural areas in particular. Definitely confirm your coverage before buying – that is to say, make sure your phone is going to work where you live.

Having absorbed these technical details, go buy yourself a high-end deli sandwich. As an Informed Consumer, you deserve it.


GSM is for Worldwide. That is why AT&T and T-Mobile have EDGE software on their plans. CDMA is only in North America. CDMA is faster with Ev-Do than a EDGE System