Samsung's Jack SGH-i637 is the latest in the company's diverse lineup of Microsoft OS-powered smartphones. This follow-up to the highly successful BlackJack II hews closely to the usual formula—a slab QWERTY handset without a touch screen—but adds a number of useful updates that make this the best BlackJack yet. It's also one of the top Windows Mobile smartphones I've seen recently—and it comes at a bargain price ($99.99 with a two-year contract), even if it doesn't quite live up to the lofty standards of comparable RIM, Apple, and Nokia smart devices on AT&T.

The Samsung Jack looks a lot like the BlackBerry Bold or the BlackBerry Curve 8900 with its metallic charcoal-gray paint and thick, tinted chrome band around the edges, even if its plastic is a little too slippery and shiny. It's on the small side for a slab smartphone. It measures 4.4 by 2.4 by 0.5 inches (HWD) and weighs 3.6 ounces. That's a good half an ounce lighter than the average BlackBerry Curve or original Motorola Q. I parked a Samsung Epix, the Jack's touch-screen-enabled older brother, nearby; the Epix looks gargantuan in comparison. The Jack's roomy QWERTY keyboard includes four rows of some of the best keys I've tried recently: They're surprisingly large and roomy, given the size of the handset, with just the right amount of click and resistance.

The LCD is a basic 2.4-inch, 320-by-240-pixel QVGA affair. There's no touch capability, which in the Microsoft world means that this phone runs Windows Mobile 6.1 Standard, not Professional. The five-way control pad, meanwhile, is touch-sensitive: Push lightly to scroll through text on a Web page, or push harder to jump between pages. There are plenty of shortcut keys around the control pad and along the bottom row of the QWERTY keyboard, but the slightly crowded look worked fine in practice. The sides contain power and volume controls, along with a covered proprietary headphone and charger port.

The Samsung Jack is a quad-band EDGE (850/900/1,800/1,900 MHz) and tri-band UMTS/HSDPA (850/1,900/2,100 MHz) world phone. It also includes a Wi-Fi radio, so you'll never lack for connectivity. On my tests, voice quality on the Jack was warm, loud, and natural sounding in both directions. The phone's reception was also good. In a rural area of Massachusetts, the Jack had no problem locking onto AT&T's 3G data network with two bars of signal strength, while a nearby iPhone 3G stayed solidly in EDGE mode. The Jack also paired with a Plantronics Voyager Pro Bluetooth headset on the first try and sounded good through it. The Jack's speakerphone was suitably loud for outdoor use, although it distorted some syllables at the highest volume setting. Battery life was truly impressive at 6 hours 35 minutes.

The Jack includes a 528-MHz processor, 256MB ROM, and 175MB RAM, with a roomy 141MB free for user programs. Those specs trounce the BlackJack II's sluggish 260-MHz processor and 128MB maximum RAM. The home screen is cluttered, as with most Windows Mobile smartphones, but it's pretty easy to get around due to the excellent hardware control pad. What's more, the UI is unusually responsive because of the fast CPU. Still, some of the usual Microsoft-related bugaboos remain: The UI sometimes hangs for seconds at a time with a spinning wheel; fixed UI bars at the top and bottom of every screen interfere with apps and take away precious screen resolution, which is low to begin with; and I had to contend with plenty of unnecessary dialog boxes, including one for Microsoft's Customer Experience Improvement Program, and one hard crash (which I'll get to in a moment). The Jack's built-in GPS chip supports the TeleNav-powered AT&T Navigator, which offers voice-enabled, turn-by-turn directions for $2.99 per day or $9.99 per month. For Web browsing, you're saddled with Internet Explorer Mobile, which is sluggish and good only for viewing WAP sites.

For messaging, the Jack supports threaded two-way text messages and has a one-touch messaging key on the front. As a Windows Mobile 6.1 smartphone, it synchronizes with Microsoft Outlook and Microsoft Exchange Server accounts, and offers Direct Push e-mail. On the Jack, you can view and edit Microsoft Word and Excel documents, and view (but not edit) PowerPoint documents—but you still can't create new files from scratch. There's also built-in Java support, which is unusual for a Windows Mobile phone. Interestingly, Samsung claims the Jack will be upgradable to Windows Mobile 6.5 when the new OS is released later this year; nearly all current Windows Mobile phones won't be, so that's a plus for the Jack.

As is typical for Windows Mobile, the music player supports WMA, MP3, and AAC files. The proprietary headphone jack requires an included dongle, which I found to be a pain. Music tracks sounded clear over a wired set of stock iPod earbuds; over a paired set of Motorola MotoROKR S9-HD stereo Bluetooth headphones, the sound was dull and muffled, with a disturbing amount of background hiss. Video files played back relatively smoothly for Windows Mobile, but still had a distracting smooth-stutter-smooth-stutter pattern to the frame rate. The handset's microSD card slot accepts up to 16GB cards (my 8GB SanDisk card worked fine), but you have to pull the battery to swap cards, an annoyance that's compounded by an unusually stubborn battery cover. I suggest you treat this one like an iPhone with internal memory: Buy a high-capacity card, install it once, and then sync with a USB cable from then on.

The Jack includes a 3.2-megapixel camera, but no flash or autofocus features. The first time I fired up the camera and tried to take a photo, the entire handset hard crashed with a "FATAL ARM9 ERROR" message. I had to pull the battery and restart to clear the error. But after that, things went well. Test photos were very detailed and looked quite sharp outdoors but fell down a bit indoors in dim lighting, where large swaths of each picture were entirely black. The shutter speed was also a little slow; a number of photos were too blurry to be usable, even when I stood perfectly still. Recorded 3GP videos at 320-by-240-pixel resolution were smoothly animated. But, again, only the ones recorded outdoors or indoors with bright lighting were usable—others were way too dark.

With the carrier's powerful smartphone lineup, you certainly won't want for options on AT&T. The iPhone 3G is our Editors' Choice handset: It offers the best mobile touch interface, media experience, and third-party app capability on the planet, at the expense of a hardware keyboard. And the upcoming iPhone 3G S adds even more features. The Nokia E71x is a fast, powerful Symbian-based smartphone and, at $149.99, another excellent value; I'd probably give this one the nod as well, owing to its superior Web browser and high-class design. The BlackBerry Bold is more similar to the Jack, though with a higher-resolution LCD and RIM's stellar push e-mail capability; but it's also heavier and more expensive ($199.99). The Curve 8310 offers the same push e-mail at the same price as the Jack ($99.99), but it lacks a 3G radio and has a more cramped keyboard than the Jack. The aforementioned Samsung Epix is a touch-screen smartphone running Windows Mobile 6.1 Professional, complete with a touchpad and mouse cursor, although it's larger, heavier, and boxier. In short, Samsung nailed the hardware and feature set with the Jack. If you're okay with the hoary old Windows Mobile OS, the Jack is a solid smartphone and a good value.

Benchmark Test Results
Continuous talk time: 6 hours and 35 minutes

Compare the Samsung Jack with several other mobile phones side by side.

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