The dual-slider is a new trend in smartphone design.  These phones have both standard dial pads and QWERTY keyboards, the first sliding out from behind the display in one direction and the second sliding out in another.  The benefit of this design is clear: access to both a dedicated dial-pad for making voice calls and a thumb keyboard for text messaging, word processing and e-mail.  The first Windows Mobile dual-slider available in the U.S. is the Pantech Duo C810 from AT&T Mobility [CHECK PRICES]. I was eager to review this device, not only because of its dual-slider design, but also because Pantech is a relative newcomer to the Windows Mobile market.  After spending a few weeks with the Duo, however, I’ve found it to be quite a mixed bag.  While the Duo’s design is innovative and allows for a generally comfortable user experience, lackluster performance and limited onboard features make this handset a far less attractive device than it might otherwise have been; that said, the Duo is still a fine choice as a basic Windows Mobile Smartphone, particularly if you can find it with a substantial discount from third-party retailers.

Design

It would be difficult to overstate my fondness for the Duo’s dual-slider design.  QWERTY keyboards are great for alphabetical input, but dialing on thumb keyboards isn’t at all user friendly.  The dual-slider approach (made famous by the Pantech-made Helio Ocean) requires the user to make no sacrifices, either in tactile dialing or data entry. 

The Pantech Duo C810 is small enough for most users to drop in their pocket, but its three layers (screen, dial-pad and keyboard) make the handset 0.8-inches thick, thicker than the typical smartphone, but about average for most clamshells.  Its exterior plastic shell has a dark gray, metallic look that lends the handset a more substantial appearance than a plastic phone might otherwise have, though it certainly doesn’t have a visual “wow” factor. 

Pushing the screen upward exposes a standard dialing pad, while sliding the screen to the right reveals the QWERTY keyboard and changes the screen to a landscape orientation.  The two sliders work independent of one another and cannot be exposed simultaneously; while they are a bit flimsy when in motion, each slider is solid enough when fully extended.  The keyboard’s blocky styling has an interesting aesthetic, but because the keys are roughly flush with the phone’s surface, it’s difficult to distinguish one key from another based on touch alone.

The Duo’s QVGA screen is bright and clear and has practically no “screen door” effect, making it one of the clearest I’ve seen on a WM non-touchscreen smartphone.  Images and fonts appear clear and crisp, and video looks pretty darn good on the 2.2-inch display.    

 

Features

The Pantech Duo C810 has a disappointing feature set which stands in stark contrast to its excellent dual-slider design.    There’s no Wi-Fi or GPS receiver.  The onboard Bluetooth is v1.2 rather than 2.0, and is not compatible with wireless DUN.  There’s only 128MB of flash memory storage and 64MB of system memory onboard.  The microSD card slot is not compatible with higher-capacity SDHC cards like the majority of Windows Mobile 6 devices.    The onboard camera captures only 1.3 megapixels.   Each of these omissions would be excusable in isolation, but the sum of the missing parts makes for limited functionality beyond basic Windows Mobile operations.

One Duo feature that is not at all mid-range is its Broadband data connectivity.  In addition to GPRS and EDGE, the Duo is compatible with UMTS/HSDPA data networks, for a max downstream speed of 3.6Mbps.  This makes data performance snappy if you live or work in an area with UMTS/HSDPA network coverage.   Unfortunately, you cannot use the Duo as a modem for your Windows PC via Bluetooth, but you can connect via USB; this requires the use of AT&T’s Connection Manager software, which is aggravating and senseless considering how well Windows Mobile 6 generally manages Internet sharing.

 

The Phone The Pantech Duo’s call quality is better than average, though not stellar.  Calls can sound a little grainy through the Duo’s earpiece at times, and voices on the other end of the line sometime sound cloudy and distant.  Callers on the other end, however, generally reported very good sound quality from the Duo’s mic, so again, it’s a mixed bag. You can use the sliding dial pad to make calls, of course, but you can also answer and end calls with the dial pad hidden thanks to the on-face Talk and End buttons.  Dialing with the pad is easy and solid, and there may not be enough room to accommodate those with larger fingers.

 

Software

The Duo runs the Windows Mobile 6 Standard operating system, the version of Windows Mobile designed for non-touchscreen smartphones.  WM6 Standard includes e-mail and text messaging software, Internet Explorer Mobile, Windows Media Player Mobile, calendar, contacts, and tasks, a file explorer utility and games.  In addition to the standard complement of applications, the Pantech Duo also includes some media “applications” like AT&T Music and Cellular Video (which are nothing more than Internet links to music downloads and online videos), and Shazam’s fantastic MusicID software which can identify a song playing on the radio simply by sampling a short portion of the audio.  XM Radio software, which streams selected XM channels over the Internet, is also included, though you have to pay for the service.  Ditto for MobiTV, which is also pre-installed.

Third-party productivity applications are few and far between on the Duo, though there are some notable titles.  A Java Virtual Machine (JVM) is included for running Java applications such as Gmail and Opera mini.  ClearVue PDF also allows you to view PDF files on the Duo, though because of the unit’s relatively slow processor, I’d keep those PDFs rather small if I were you.  You can IM with Yahoo!, AIM and Windows Live Messenger courtesy of OZ Mobile Instant Messaging and Xpress Mail is available for download directly to the handheld, which allows you to push your e-mail directly to the Duo.

 

Subjective Performance Analyses

The Duo’s 412MHz processor doesn’t seem as speedy in actual use as it might seem on paper. I found opening applications and moving about the OS a bit sluggish at times, but within tolerance.  I enjoyed very good signal quality with the Duo, often full strength, in a location where AT&T’s signal isn’t always so bold; that said, as I mentioned before, the unit’s call quality is only on the plus side of average.  While the onboard camera is only 1.3MP, I found the quality of the small photos to be better than average.  AT&T indicates that the Duo should top out at around 3 hours of talk time, though I consistently saw 3.5 to 4 hours of talk time on a full charge.  Standby is rated at 10 hours.      

Conclusion

The time I spent with the Pantech Duo seesawed between enjoyment and mild frustration. The Duo’s dual-slider design makes for, quite possibly, the best non-touchscreen Windows Mobile Smartphone configuration thus far, but its lackluster features and slow performance make it a device that I can recommend only to those needing the most basic Windows Mobile phone.  If the unit were faster, ditched the plastic exterior and featured a Wi-Fi chip here or GPS receiver there, I could really get behind the Duo in a big way.  I’m keeping my fingers crossed for the Duo 2.

[CHECK PRICES: Pantech Duo C810]

Grade: C+

Useful Dual Slider Design	No Onboard Wi-Fi, GPS
Fast 3G UMTS/HSDPA Connectivity	Sub-standard Bluetooth v1.2
Low Price from 3rd Party Retailers	microSD Not SDHC Compatible

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