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Surfing at 3G Speeds

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All smartphones can access the Web, but not all can do so at the same speed. Some mobile phones can zip from site to site, downloading files in a flash, while others seem to offers speeds no faster than an ancient dial-up connection.

Apple's iPhone, for example, can't access AT&T's HSDPA network; Apple says it chose not to include support for HSDPA because the necessary chipset would have drawn too much power, reducing battery life.

If high-speed data service matters to you, make sure that the phone you're interested in supports a 3G network. And remember to ask if you can try out the phone and the 3G service before committing to a long-term contract, or return it if you're unhappy with its performance. Remember: Actual speeds may vary.

How can you be sure your phone will offer speedy Web browsing? One of the biggest factors is the data network that your phone supports—and the network that your cellular carrier offers. A 3G, or third generation, data network will offer the fastest speeds. Not all 3G networks are created equal, however. Each cellular carrier offers its own network (or networks), and many are not available in all locations.

Here’s an overview of this often confusing technology.

Not All Phones Are Equal:

Your carrier may offer a high-speed data network, but not all of its phones can access these speedy services. Only certain handsets—those equipped with the right chipset on the inside—can do so.

Definition of 3G:

A 3G network is a mobile broadband network, offering data speeds of at least 144 kilobits per second (Kbps). For comparison, a dial-up Internet connection on a computer typically offers speeds of about 56 Kbps. If you've ever sat and waited for a Web page to download over a dial-up connection, you know how slow that is.

3G networks can offers speeds of 3.1 megabits per second (Mbps) or more; that’s on par with speeds offered by cable modems.

In day-to-day use, however, the actual speed of the 3G network will vary. Factors such as signal strength, your location, and network traffic all come into play.

T-Mobile Lags Behind:

Currently, T-Mobile only supports the 2.5G EDGE network. The carrier plans to launch a 3G network, with support for the high-speed HSDPA service, later this summer, however. Stay tuned.

AT&T's High-Speed Service:

AT&T offers three "high-speed" data networks: EDGE, UMTS, and HSDPA.

The EDGE network, which is the data network supported by the first-generation iPhone, is not a true 3G data network. It's often referred to as a 2.5G network, with speeds that don’t exceed 200 Kbps.

The UMTS service offers speeds of 200 Kbps to 400 Kbps, with the possibility to top out at about 2 Mbps. It's a true 3G service with speeds that surpass those of the EDGE network.

Sprint Nextel and Verizon Wireless:

Sprint Nextel and Verizon Wireless both support the EV-DO network. EV-DO is short for Evolution-Data Optimized, and is sometimes abbreviated as EvDO or EVDO. EV-DO is rated to offer speeds from 400 Kbps to 700 Kbps; as with the other 3G networks, actual speeds vary.

The differences between the EV-DO service offered by Sprint Nextel and that offered by Verizon Wireless are minimal. Speeds are comparable, but each carrier offers coverage in slightly different areas.

See Sprint's coverage map and Verizon's coverage map for more information on network availability.

HSDPA is the fastest of the fast networks. It's so fast that it's often called a 3.5G network. AT&T says the network can hit speeds of 3.6 Mbps to 14.4 Mbps. Real-world speeds typically are slower than that, but HSDPA is still a super-fast network. AT&T also says that its network will hit speeds of 20 Mbps in 2009.

For more information on network availability, check out AT&T's coverage map.

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