UMTS is an entirely new setup based on CDMA, which is why roll-out has been slow; Cingular's faster EDGE roll-out was a mere software upgrade to GSM.

Whereas GSM networks segregate calls into exclusive time slots, CDMA networks mix a bunch of calls together into a single channel, with each call encoded with a special key. (Think of it as a group of people in a room, each speaking loudly in a different language. Only the decoder with the right key—the one that speaks the right language—can understand each call.)

UMTS is also known as WCDMA (Wideband CDMA) because it uses wider channels than standard CDMA. It mixes voice and data in channels and allows for packetized voice—turning voice into data to pack more calls into each channel.

UMTS has a maximum theoretical download speed of 384 Kbps, but we didn't get anything approaching that on our San Francisco and Dallas tests. Using the Novatel Wireless Merlin U520 PC Card ($ direct with a one-year contract), we topped out at 299 Kbps—not much faster than EDGE. And upload speeds were especially disappointing, averaging 54 Kbps, very similar to our EDGE devices.

Cingular is aware it needs to boost UMTS's verve, so it's already working on an upgrade, HSDPA. HSDPA is a software upgrade to UMTS that uses more advanced coding techniques to achieve average data speeds of up to 700 Kbps. (In theory, HSDPA can zip along at up to 14 Mbps, but that depends on network configuration.) Cingular says it will roll this out in 2006. T-Mobile has also said it will upgrade to UMTS/HSDPA, perhaps by 2007.

We got a glimpse of the true future of UMTS while traveling in Asia. In Hong Kong, we used the LG U8120 handset on Three's UMTS network. The U8120 is the size of an ordinary flip phone but lets you make clear, two-way video calls—even when you're roaming internationally. We also liked Three's business finder, which used tower-based GPS to tell us where the nearest noodle shop was. Cingular's network doesn't have those features yet, but we expect to see them in the future.

If you want to try UMTS in the ., you can do so with a handset or a PC Card. The Merlin U520 PC Card for laptops gives you easy access to the Web for $79 per month.

Cingular also offers two huge, unwieldy handsets, both of which can be used as laptop modems: the Nokia 6551 ($299 direct) and the Motorola A845 ($299). The A845 is the better of the two, though it feels like a piece of construction equipment. Cingular is working with LG, Motorola, and Nokia on delivering smaller, more flexible phones by the end of this year.

Even though many countries in Asia and Europe are going with UMTS as their next-generation network, this doesn't mean your phone will automatically work there. In the ., UMTS signals are transmitted on the 1,900-MHz frequency band, while most other countries use 2,100 MHz. Look for UMTS world phones later in 2005.

As with Verizon's V Cast EV-DO service, Cingular lets you stream movie previews, news clips, and music videos to the A845, though we weren't thrilled with the video quality. Unlike Verizon's phones, the A845 has instant messaging, e-mail, and Bluetooth, and you can link it up to a Bluetooth-equipped laptop as a modem. This more open approach is vastly preferable to the restricted V Cast service, which right now lets you only watch video clips.

UMTS service on the A845 costs $ per month in addition to your voice plan, plus $1 per megabyte if you hook your phone up to a laptop. Those on a tighter budget should hold off on the A845 and get the Nokia 6230 ($ with contract) with MEdia Net unlimited EDGE instead. That plan is less expensive, the network covers the whole country, the handset is much smaller, and data speeds are only about 15 percent slower.

We like the potential of UMTS: global roaming, handsets that can be tethered to laptops, and innovative services that combine voice and data. But unfortunately, that potential just is not realized with today's limited coverage and clunky phones. We look forward to seeing Cingular develop a more compelling, wider-reaching 3G service.