In Brief

If you spend a lot of time on the road, the Sony Ericsson GC82 EDGE cell data card will let you connect at reasonable speeds with wide coverage, eliminating the need to find a Wi-Fi hotspot or wired phone line. While throughput is much less than that of Wi-Fi hotspots (typically 100-130 Kbps downstream, 30 Kbps upstream), it's much faster than earlier cellular data services. That said, the cost of the card (anywhere from $0 to $300, depending on rebates) is negligible compared to the $80/month you'll pay for unlimited data, and actual speeds can vary tremendously.

In Depth

If you've used earlier data services like CDPD, CDMA or GPRS, you may be soured on the whole concept of connecting your laptop or PDA to the Internet via a cellular connection. Those services hardly even matched wired dialup speeds, ranging from a minuscule 10 Kbps to 40-70Kbps at best, barely tolerable for light Web surfing and email. Spotty coverage and network latency also made for a frustrating experience.

All of this changes with the new generation of cell cards, which can deliver speeds in the hundreds of kilobits per second. There are two leading high-speed cellular technologies: EDGE for GSM networks, and 1x EV-DO for CDMA networks. EDGE delivers up to 240Kbps, and 1x EV-DO promises 300 to 500 Kbps.

However, EDGE is widely available now in major cities, while EV-DO is currently in the testing phase, available only in San Diego and Washington, DC. (Verizon Wireless, which offers EV-DO service in the US, promises major cities will be covered by year's end.)

If you're curious to know how GSM's data speed improved twenty-fold, here's a quick explanation: GSM operates using a technology called TDMA, or time-domain multiple access, which transmits multiple phone calls or data sessions in discrete slices of network time (timeslots). GSM phones can squeeze 9 to 13 Kbps into each slice, and GPRS combines timeslots to get around 40 Kbps total. EDGE boosts the payload per timeslot up to around 60 Kbps, yielding up to 240 Kbps for cards with four slots. When EDGE is not available, data cards fall back to GPRS speeds.

AT&T offers GPRS/EDGE service for the GC82 card. By contrast, competing GPRS phones and modem cards top out at 40 Kbps, and CDMA phones and modem cards generally surf between 50 and 70 Kbps, but can get up to 144 Kbps in 1x mode, EV-DO-capable cards promise up to 500 Kbps in the limited areas where that service is available.

These speeds, while faster than dialup, are still nothing compared to DSL, cable, or a dedicated line such as a T1. With EDGE, you'll be able to transfer a megabyte in just over 30 seconds at peak throughput. However, it will more likely take about a minute at typical speeds, and if you fall back to GPRS speeds (depending on EDGE coverage areas), it could take three and a half minutes or more. By comparison, a one-megabyte download using Wi-Fi and a cable modem takes about 7 seconds.

Furthermore, the connections are asymmetric; download speeds are two to four times higher than upload speeds due to the different numbers of timeslots assigned, typically one or two slots for uploading, and three or four for downloading. So if you frequently need to upload large photo files, for example, it may make a lot more sense to head for the nearest Wi-Fi hotspot. Still, the GC82 card offers a lot more bandwidth than EDGE phones. While you can also use an EDGE phone as a modem for your computer with a cable and software drivers, current EDGE phones offer only two or three downstream timeslots.

So, is the GC82 worth the $80 per month that Cingular and AT&T Wireless ask for unlimited data service? To answer that question, think back to recent trips you've taken where you needed to get online. Were you able to find a Wi-Fi hotspot wherever you needed one? Or if you used another cellular data plan (see JiWire's Cell Data feature) to get online, was it fast enough for you?

If you're a Windows user constantly thirsting for connectivity, and you travel mostly within AT&T's coverage area, the GC82 is an excellent choice.