Speedy 3G cellphone service, the kind that smart phones crave, can feel a bit sluggish if you live in Baltimore. Sprint picked the city to test out its "4G" network. To explain the difference between the many Gs that litter cellphone marketing, let's start with the baseline.
2G: Nearly all cellphones in America run off at least 2G - or "second generation." But the term encompasses two different technologies. Verizon and Sprint Nextel use CDMA service. T-Mobile and AT&T prefer GSM, which can be identified easily by the SIM card hidden underneath each phone's battery. The two services are very similar but not compatible. This can make life frustrating for travelers, since most of the world relies on GSM, while the US offers better CDMA coverage, especially in rural areas.
2.5G: As America transitions to 3G service, phone companies have invented ways to amp up their regular connections, creating what many call a "half" generation. Basic 2G tops out at 144 kilobits per second - fast enough to download songs in a matter of minutes - but 2.5G EDGE nearly triples that speed. Not bad. However, true 3G surpasses 2,000 kilobits per second.
It should be noted that these numbers are under "ideal conditions," something that only those in lab coats get to enjoy. The rest of us need to deal with hills and valleys, everyone else hogging the system's attention, and the cell tower trying to follow you while you're on …