The AT&T USBConnect Mercury offers a clean, compact design and exceptional upload speeds. While Web pages took a bit longer to load with this card than with some competing devices, it's a good all-around device for AT&T customers looking for a free card.
The USB Connect Mercury most closely resembles a USB thumb drive; at 2.6 x 1.0 x 0.7 inches, it's not much larger and even packs a microSD slot for additional storage. We like that it has a minimal amount of external lighting, so it wasn't annoying to use in dark environments on the way home from work. Unlike the Verizon Wireless USB727 Modem, it has no obtrusive pop-out antenna. Plus, the necessary drivers install directly from the unit itself.
On the 21st floor of an office building with 4 bars of 3G connectivity, the USBConnect Mercury really shined. It was able to upload a 25MB file at a rate of 1.1 Mbps; that's faster than any other connection card we've tested recently. The second fastest was the Verizon Wireless KPC680, which uploaded at half that speed (537 Kbps) in the same environment. However, the Mercury's 620-Kbps download speed was in the middle of the pack. It bested the Sprint Merlin EX720 and Verizon Wireless USB727, which could muster only 321 Kbps and 370 Kbps, respectively, but it fell short of the Sprint Compass 597 (785 Kbps) and Verizon Wireless KPC680 (804 Kbps). The USBConnect Mercury's Web site load times were also poor: it loaded CNN.com in 23 seconds, NYTimes.com in 25 seconds, and ESPN.com in 33 seconds.
Underground in New York's Penn Station, with 3 bars of 3G service, the Mercury's download throughput was third to last. It downloaded the 25MB file in 7 minutes and 5 seconds, or 475 Kbps, and uploaded it in 5:01, or 664 Kbps. The Verizon Wireless USB727 had a faster download time of 2:06 (1.6 Mbps).
Out in Long Beach, Long Island, the USBConnect Mercury had blazing-fast upload speeds: it uploaded our test file in 2 minutes and 13 seconds, a speed of 1.5 Mbps. The next closest was the AT&T Option GT Ultra Express, which had an upload rate of 1.3 Mbps. However, its 880 Kbps download speed was about average compared with the rest.
The AT&T USB Connect Mercury is the best option for those who frequently need to get images or videos up to FTP servers quickly. Its download speeds were decent, but nothing to write home about when compared with other cards. Considering it's free with a two-year contract and $100 mail-in rebate, though, this is a budget modem worth considering.