Money-Saving Cell Phones Do Voice Over Wi-Fi

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I have dead spots in my home--no matter what I try, certain corners just can't get cellular phone service. But my Wi-Fi network is strong throughout the house. Sound familiar? Therein lies the appeal of seamlessly roaming between Wi-Fi and cellular networks: Your wireless network can do the heavy lifting when your cellular network cannot. Fortunately, the first dual-mode phones and services that can span the two wireless spectrums are finally here, as Research in Motion's forthcoming BlackBerry 8820--due out in August through AT&T--joins the already-shipping Nokia 6086 and Samsung T409 (both offered via T-Mobile).

Early Wi-Fi-to-cellular systems focused more on large businesses, but these new phones use Unlicensed Mobile Access (UMA) technology to hand off voice calls between the GSM cellular network and a non-carrier-specific local area network (including both Bluetooth and Wi-Fi). These new UMA-equipped handsets won't cost much more, if any more, than standard models--and they can save you a bundle on airtime costs and service headaches.

The Wide World of Wireless

T-Mobile is the first nationwide provider to offer UMA, under its HotSpot @Home program. Cincinnati Bell is offering a similar service as a local provider. Both services let you add the Wi-Fi feature for $10 a month over standard voice plans. T-Mobile even goes so far as to supply an optimized D-Link or Linksys router to simplify taking calls over Wi-Fi.

With either service, you can make Wi-Fi calls from your home network, from the provider's own hotspot networks, or from third-party Wi-Fi networks (you'll have to manually configure the handset to tap into these). When your call hops to the wireless network, you won't be charged airtime use as you would if you were using the cellular network.

Wi-Fi calling can be a major boon for international travelers: If you're overseas and using a Wi-Fi network, calls to U.S. numbers will be treated as normal (you'll get hit with roaming fees only if you call an international number). It can also benefit businesses, which already have wireless networks in place.

AT&T, the nation's other GSM network, hasn't formally announced UMA service, but that offering may be forthcoming. Later this summer the company will be carrying RIM's BlackBerry 8820, which is particularly well suited for data use as well as voice over a Wi-Fi network. For one thing, the 8820 is a typical BlackBerry, with a dedicated keyboard and a screen large enough for comfortable e-mail and Web surfing. (The Nokia and Samsung phones lack a keyboard and a roomy screen.) For another, the device includes 802.11a as well as 802.11b and g; 802.11a tends to have less interference than b and g do, and it can provide better compatibility with business networks.

Service providers offering this type of Wi-Fi-to-cellular support must add a UMA controller to their network and offer cell phones with Wi-Fi radios and UMA software included. Adding UMA to a handset costs only a slight premium for handset makers.

Wi-Fi Use Going Gangbusters

The timing for dual-mode phones and services may be just right, given that half of U.S. homes have broadband, and Wi-Fi networks--both at home and around town--are increasingly prevalent.

Since UMA is still in its infancy, Nokia, RIM, and Samsung all report that they need to refine their hardware to function with different UMA networks. "There's a lot of interoperability testing to make sure that the UMA software stack in the device works with the specific carrier's UMA network," explains RIM's Mike McAndrews, vice president, product marketing. "At this stage, it would be difficult to say that there's a generic implementation of UMA that works seamlessly on all UMA networks worldwide."

While some forecasts indicate rosy times ahead for UMA-based voice over Wi-Fi, not all analysts are gung-ho about UMA. Gartner Group's Philip Redman, research vice president, doesn't see people replacing their landline phones anytime soon, and notes that the technology may be slow to gain traction given the continuing popularity of CDMA networks over GSM. Redman also points to potential quality-of-service issues. For example, if you're relying on your home Wi-Fi network for your phone calls, what do you do when your network slows down because someone else is downloading a high-definition movie or playing multiplayer online games? "I don't believe they provide any bandwidth or QoS management at all," Redman posits. "Same in public spaces--you're at the mercy of whoever is running the network."

Nonetheless, even if you're not on a network that implements UMA, you may see a positive impact on your wireless bill's bottom line. "I think providers will be more aggressive about offering cheaper and better services that are cellular-based as opposed to integrating Wi-Fi services," says Redman.

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