The 4G Mobile Hotspot is about the size and shape of a small flip cell phone (folded shut), and it weighs 2.6 ounces. In my tests, the device didn't always live up to T-Mobile's speed claims, but connections were fairly reliable and battery life was pretty good, making the product a great choice for people whose travels tend to occur within T-Mobile's area of 4G coverage (as indicated on the carrier's ).
Manufactured by China's ZTE Corporation, the 4G Mobile Hotspot also has a few extra features that some competing devices lack. You can use the unit to send and receive text messages via its browser-based interface. You can use it as a USB modem by tethering it to a PC with the included Micro-USB cable. And while that cable is connected, you can load files onto the MicroSD card slotted in the ZTE hotspot, though you'll have to bring your own card because ZTE doesn't provide one. Ultimately, this feature seems a bit pointless, since you can access the files on the card only while the hotspot is tethered to the PC.
Encased in shiny black with a few lime-green accents, the 4G Mobile Hotspot sports a small white-on-black LCD display that provides brightly lit status information, including mobile broadband network type (4G, 3G, or EDGE), strength of network connection (the usual "5 bars" icon), battery level (4 bars), Wi-Fi status (on/off), number of devices connected via Wi-Fi (represented by a small number), and newly arrived text messages (a number also tells you how many there are).
This information appears when you first power on the device, but the screen goes dark after a few moments, presumably to conserve battery life. While using the 4G Mobile Hotspot, however, you can bring up the status info by pressing the on-off button on the side of the unit. A small removable plastic doorway on the opposite edge conceals a connector for an optional external antenna, which can improve reception.
On the same edge, but on the other side of the MicroSD card slot, is a button for setting up security using WPS (Wi-Fi Protected Setup)--the Wi-Fi Alliance-backed setup protocol--if the device you're connecting to the hotspot also supports it.
You connect your devices to the ZTE hotspot and choose the security settings manually, as you would with any other Wi-Fi network that you were joining for the first time. The default network ID and encryption key are written in the battery compartment (it's a good idea to write them down so you don't have take the back panel off more than once), but you can change them in the browser-based settings pages.
You can access the settings either by installing an application while connected in USB mode (the app is in the hotspot's internal memory), or while connected wirelessly, by typing http://mobile.hotspot in the address field of your browser. The settings are fairly typical of a Wi-Fi router, aside from the above-mentioned text-messaging feature. However I doubt that text messaging support will be a big draw because you have to launch a browser to use it, and most people are likely to prefer to use their normal cell phone for this service.
The 4G Mobile Hotspot's performance varied across a wide range in my tests, which isn't unusual since many variables--including proximity to the cell site and the amount of traffic the site is handling at any given moment--affect both Wi-Fi and mobile broadband speeds. But even the fastest download speed results I recorded (using speedtest.net) fell short of the rates of 5 to 8 megabits per second (with even higher bursts) that the company says are typical.
In one set of tests, both downloads and uploads hovered between 2 and 4 mbps; in another, I occasionally saw passes exceeding 4 mbps. The overall averages in my tests were 2.8 mbps for downloads and 2.2 mbps for uploads. Even so, the hotspot let me stream Netflix movies with almost no difficulty--though at one point during each film, the unit went to sleep for some reason, causing the film to stop.
Tests on my iPhone using the produced similar speed results (averages were 2.7 mbps for downloads and 2.6mbps for uploads), but latency on the iPhone connected via Wi-Fi to the same hotspot was more pronounced, with an average lag of 141 milliseconds versus about 71 milliseconds on my notebook PC.
Handoffs between different generations of wireless networks were a bit awkward: The unit seemed to need a few moments to fix on a 4G signal when I drove around, though I detected no disconnects. It seemed very sensitive to changes in network signal strength, however, as the number of bars varied often as I drove through coverage areas.
The T-Mobile 4G Mobile Hotspot uses 802.11b/g Wi-Fi rather than the newer and faster 802.11n standard. Since 802.11g networks are much faster (typically at least 10 mbps in real-world throughput) than T-Mobile's HSPA+ network, the lack of 802.11n support won't slow down Internet applications. An 802.11n Wi-Fi network also generally covers a wider area than an 802.11g network does, allowing connections from farther away from the hotspot. But in my informal tests, T-Mobile's coverage range was quite good, extending at last 50 feet down the hallway of my apartment complex without breaking the connection.
Battery life was a pleasant surprise: T-Mobile promises 4 hours of continuous use, and the unit definitely achieved that mark. I streamed two feature-length movies from Netflix and still had enough juice left over to check e-mail--all on a single battery charge. It takes a couple of hours to fully charge the unit via the Micro-USB cable, which you connect either to a PC or to an included plug for a standard wall outlet. While charging, the display shows a flashing battery icon that stops flashing once the 4G Mobile Hotspot is fully charged. You then turn on the unit by pressing a small button next to the MicroSD card slot on the side of the device.
T-Mobile offers two mobile broadband plans, both of which include unlimited free access to T-Mobile's own Wi-Fi hotspots: The $85-per-month plan gives you 10GB of Web access, while the $50-a-month plan tops out at 5GB--but only for 4G connections. If you reach the bandwidth limit, T-Mobile doesn't charge for overage--it simply slows you down to 3G speeds. There's no bandwidth limit for 3G or EDGE connections. Occasional users can opt to pay more for the device ($130) and purchase 100MB, 1GB, or 3GB prepaid passes (for $10, $30, or $50 respectively).
The most annoying thing about the 4G Mobile Hotspot is its occasional tendency to go to sleep without warning (as it did with the movies I streamed and with other applications). However, this didn't happen often enough to completely nullify the unit's selling points. The 4G Mobile Hotspot is easy to use, has reasonably good speed, possesses strong battery life, and is pleasingly small and slim. T-Mobile's flexible plan and prepaid usage offerings are the icing on the cake for this capable device.