Just like the T-Mobile WebConnect USB, the Verizon Wireless USB760, and the Sierra Wireless 598U for Sprint, the AT&T USBConnect Mercury offers Internet connectivity on the go via cellular or Wi-Fi connection. Compact and simple, the portable modem is great for anyone who works on the road but, we'd recommend getting one of the aforementioned products before the USBConnect Mercury. Coverage could be spotty at times and download and upload speeds were often slow, which made it quite frustrating to use and not even worth the free price tag (with a two-year contract and after rebates). Also, like the other adapters, the AT&T USBConnect Mercury requires a data plan--$60 per month for 5GB of data--but be aware that AT&T charges $0.49 per MB for overage fees, which is considerably more than T-Mobile, Sprint, and Verizon.
Manufactured by Sierra Wireless, the AT&T USBConnect Mercury measures 2.6 inches tall by 1 inch wide by 0.7 inch deep and weighs just 1.2 ounces. To help you keep track of the little guy, AT&T ships the portable modem with a carrying strap that you can attach to the removable cap, which protects the USB connector, and then clip onto your body or bag. There's an external antenna jack on the right side of the device, and on front, you'll find two LEDs: the left one stays a solid blue when powered on and the right blinks or remains a solid orange or blue depending on network activity.
Like the others, the USBConnect Mercury is a plug-and-play solution that you can connect to your laptop just like a flash drive. In fact, the modem has a built-in microSD expansion slot so it can double as a storage device; AT&T has tested with up to 4GB cards but, according to Sierra Wireless, it can support up to 32GB. However, we weren't so fond of the location of the expansion slot or the SIM card slot. Both sit right above the USB connector so it's difficult to insert and remove either card just by hand. We much prefer the other carrier's modem designs, which have the expansion slot located either on the side or bottom.
When you first connect the USBConnect Mercury to your laptop (compatible with machines running Windows Vista, XP and 2000; Mac OS 10.4.11 or later), it will automatically launch and install the necessary drivers and software to your computer. While there's very little action required by the user, the installation process does take a while; in fact, AT&T notes in its documentation that it takes about 10 minutes.
Once installed and after restarting your computer, you should find the AT&T Communication Manager on your desktop. There you can connect to AT&T's network or any available Wi-Fi networks. Like the T-Mobile WebConnect and Verizon Wireless USB760, you can also use the software to send, receive, and manage text messages with a cellular connection. The software interface is dead simple with two main tabs GSM or Wi-Fi. There are also options to manage your connections, set up a VPN, run diagnostics, and more. Unfortunately, the modem does not offer integrated GPS like the Sierra Wireless 598U.
The AT&T USBConnect Mercury supports the carrier's EDGE (850/900/1,800/1,900MHz) and HSDPA (850/1,900/2,100MHz) networks; AT&T claims to have the fastest 3G network and says its typical download speeds range between 700Kbps and 1.7Mbps and upload speeds in the 500Kbps to 1.2Mbps range. However, when compared with the competing carriers' offerings, we found the USBConnect Mercury to be the most frustrating to use because of the inconsistent coverage and pokey speeds.
We tested the modem on our Lenovo ThinkPad T61 throughout San Francisco, and the 3G coverage was really spotty and it wasn't uncommon to have six bars of coverage one minute and then down to one or two bars the next. As we've done with other cellular modems, we ran tests using Speedtest.net and the USBConnect Mercury offered an average of 1.24Mbps for download speeds but a lowly 320Kbps for uploads. Perhaps more telling, with a signal strength of -70dbm, it took 2 minutes and 28 seconds for CNET's site to fully load while CNN.com took 1 minute 30 seconds, ESPN.com 1 minute 40 seconds, and NYTimes.com 1 minute 31 seconds. The T-Mobile WebConnect, Verizon Wireless USB760, and Sierra Wireless 598U for Sprint loaded all the same sites in 30 seconds or less. After having experienced better, we just can't see a reason to choose the USBConnect Mercury over the others.