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.