Hands on: T-Mobile's mobile hotspot offers speed and flexibility

Computerworld - No. 4 wireless carrier T-Mobile has just joined its larger rivals in offering its customers a mobile hotspot. These handy devices tap into your cellular service, broadcasting a Wi-Fi signal that lets you connect up to five laptops, tablets or other devices to the Internet, effectively creating a personal high-speed wireless network wherever you go.

I recently tested mobile hotspots sold by Sprint, Verizon Wireless and AT&T to see which device -- and network -- served up the fastest speeds and packed in the best features. While AT&T's Novatel Wireless MiFi 2372 was the cheapest and Sprint's Novatel MiFi 4082 had the longest battery life, the Samsung SCH-LC11, backed by Verizon's LTE network, was the clear speed winner.

How does the T-Mobile 4G Mobile Hotspot ZTE MF61 stack up?

The network

T-Mobile is a bit optimistic in calling its network 4G. Based on HSPA+ technology, an upgrade to the company's HSPA 3G technology, most of T-Mobile's network is capable of a maximum throughput of 21Mbps, well short of the peak bandwidth of more than 100Mbps that is theoretically possible with Sprint's WiMax and Verizon's LTE networks. As is the case with AT&T's HSPA+ network, it's best to call T-Mobile's 3.5G. (See "The 4G name game.")

But real-world speeds can be significantly lower than theoretical ones, and a 3.5G network can beat a 4G network under the right circumstances. More about that in a moment.

Meanwhile, T-Mobile is busy rolling out even faster HSPA+ 42 service with a peak theoretical throughput of 42Mbps -- twice that of the original HSPA+ 21 network. The new network is currently available in just under 100 cities, from Akron, Ohio, to Waco, Texas.

T-Mobile's new mobile hotspot doesn't, however, work with the HSPA+ 42 network, so all my tests were conducted on the more widespread HSPA+ 21 network. Which leads to my next point: For the hotspot to work, T-Mobile's network must be available where you live (or where you travel), so be sure to check the company's coverage map. Like the other networks, T-Mobile's is strongest on the coasts and in major cities.

Further muddying the waters is the fact that AT&T intends to buy T-Mobile and make use of both companies' networks. The merger must still pass muster with the U.S. Department of Justice and the Federal Communications Commission. If it does go through, it remains to be seen whether the companies' mobile hotspots and networks will interoperate.

Three views of the T-Mobile's 4G Mobile Hotspot

The device

T-Mobile's hotspot is attractive and easy to use. Measuring 0.6 by 3.9 by 2.1 in. and weighing 2.9 oz., the T-Mobile hotspot is a fraction of an ounce heavier than AT&T's Novatel MiFi 2372 hotspot but lighter than Sprint's Novatel MiFi 4082 device. I really like the bright green edge that gives it a splash of style.

Rather than cryptic blinking lights to show what it's doing, it has a small, bright information screen that displays a four-bar battery gauge, the network's signal strength, Wi-Fi status and how many clients are connected.

Unlike the hotspots from AT&T, Sprint and Verizon, T-Mobile's works with 802.11b/g only; it can't use the newer and potentially faster 802.11n protocol for Wi-Fi. The router can support up to five clients, but it lacks the GPS location abilities that the other three hotspots have.

On the other hand, the T-Mobile hotspot can do something the others can't: It has a connector to plug in an external antenna to boost a weak signal. The antenna is available from third-party sellers for $50.

Like the AT&T and Sprint hotspots, the MF61 has a handy microSDHC card slot that lets connected users share data. It works with cards that hold up to 32GB of data. The hotspot supports Windows and Mac OS X computers. (Next: Performance)