T-Mobile isn't the first U.S. carrier to offer the Wi-Fi-equipped BlackBerry Pearl 8120 (AT&T Wireless launched its 8120 earlier this year), but T-Mobile's version has a decidedly consumer spin. Thanks to T-Mobile's innovative HotSpot@Home technology, this Pearl also lets you make VoIP calls over Wi-Fi.

The voice-over-Wi-Fi feature improves reception in locations where cell signals are weak, and in my tests the technology (called Unlicensed Mobile Access, or UMA) worked very well; the only visible indication that the phone was not using T-Mobile's cellular network for calls was the Wi-Fi network's SSID on the screen. Clearly, if you're within hotspot range, Wi-Fi speeds up Web browsing and data-intensive tasks, too. However, using Wi-Fi for voice calls requires T-Mobile's $10-a-month HotSpot@Home Talk Forever Mobile service, an add-on that is not available for the carrier's least-expensive plans.

I found the T-Mobile 8120 ($200 with a two-year contract) less handsome than the AT&T version, in part because of its mousy-grey case; the icons in the BlackBerry menu looked cartoonish, as well. The cluttered interface is mostly a result of all the software T-Mobile loads on the device (AT&T's applications folder on its Pearl makes things cleaner). Instead of this interface, MyFaves subscribers can go for tiny images of their MyFaves buddies (five people that you can spend unlimited time talking to).

On the other hand, I liked the software itself, which included a voice-command application that worked very well for dialing contacts; a couple of games; and RepliGo software for viewing, printing and faxing Microsoft Office documents. And all the features I appreciated in the AT&T 8120--the sharp 2.0-megapixel camera, the excellent multimedia player, and the SureType predictive text-entry system for typing on a 20-key keyboard--remained impressive. (SureType is something you should try out for yourself, however; some of my colleagues don't like SureType as much as I do).

Both voice quality and talk-time battery life were excellent: The T-Mobile 8120 lasted 10 hours in our lab tests, the maximum amount of time we test.

Looks are a big reason for buying a Pearl, so I'd like to see T-Mobile offer a snappier-colored case. The user interface should be neater, as well. But with its quad-band GSM/GPRS/EDGE and Wi-Fi support, T-Mobile's 8120 remains an intriguing option for people who want a small phone with the ability to pick up data speed when Wi-Fi is handy.

--Yardena Arar