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The Two Faces Of Dual-Mode Handsets

By Ben Guderian


Dual-mode handsets mobile telephones that work on both cellular and WiFi networks are a hot topic in wireless telephony today. The proliferation of WiFi access, both in homes and public hotspots, has driven interest in using WiFi to augment or substitute for cellular networks. WiFi can't totally replace cellular, mostly because cellular technologies were designed specifically for covering large geographic areas while WiFi is more suited to in-building coverage or dense urban deployments. So don't plan on trading in your cell phone for a WiFi-only telephone just yet, unless you don't need to be accessible in the car or walking between hotspots. To really take advantage of what both cellular and WiFi technologies have to offer, you'll need a handset that supports both kinds of networks.

The idea of a dual-mode handset isnt new. Almost ten years ago, Ericsson offered a handset supporting both GSM cellular and DECT cordless technologies. BT offered their Onephone service, which tied their cellular service with DECT, but it never took off partially due to the lack of support from handset manufacturers. So whats changed? Most importantly, WiFi is an IP-based packet data technology, so unlike DECT it can be used for broadband data applications like Internet access. Also, DECT didnt have the global availability and widespread industry support WiFi has today.

Several handset manufacturers are already shipping or have announced dual-mode products, and its likely that others are on the drawing board or in development. Most of the dual-mode devices available today are high-end cell phones or PDAs with WiFi primarily for broadband data access, although some are incorporating WiFi specifically for VoIP applications. It isnt very complicated to add a WiFi radio module to a cell phone, although as with any WiFi client device, there are still the challenges of power consumption, quality of service, and security to deal with. The component manufacturers are coming up with chip sets with better integration of cellular and WiFi, which will reduce cost and improve battery life.

All in all, theres a lot of development activity, but whats really driving demand for dual-mode handsets? That depends on who you ask.

What Users Want
The opportunities and requirements for dual-mode handsets differ significantly between enterprise and consumer markets. Cellular phones have reached saturation in both of these markets, and cellular services look pretty much the same for both business and personal usage. WiFi adoption is growing in both enterprise and residential markets, also with similar applications, but with substantial differences in equipment cost and functionality.

ABI Research recently predicted that seven percent of mobile handsets shipping in 2009 will have WiFi capabilities. That might not sound like a high percentage, but it translates to an installed base of more than 50 million handsets. ABI expects that demand for dual-mode handsets will be driven primarily by enterprise users that need broadband access for data-intensive applications, and Wi-Fi is better suited for this than 3G cellular data access.

Another view comes from a recent consumer research report from In-Stat, which says that more than 80 percent of respondents were at least somewhat interested in the prospect of using a WiFi enabled cellular phone, with 50 percent either very interested or extremely interested in a dual-mode phone. The study identified better in-building coverage and unlimited calling plans as motivations for using WiFi at home.

So on one hand we have enterprise demand being driven by the need for speed (for data applications), while on the other hand we have consumers wanting better network access, and of course, saving money. Even though fundamentally its the same device, applications and services differ significantly between consumer and enterprise markets.

Putting Dual-Mode To Work
In the enterprise context, a dual-mode handset doesnt make sense for every employee. Anyone who is not given a cell phone by their employer is not a candidate for a dual-mode handset. Depending on their job function, they either dont need a wireless phone at work, or they are better served by a WiFi-only handset for use in the workplace. Employees with company-furnished cell phones who are always on the road might not need WiFi access either, since they spend little or no time in company facilities, so a single-mode cell phone meets their needs. The ideal enterprise users for dual-mode handsets are the employees that are given cell phones because they travel on business or need to be contacted during off-hours, and they need to be mobile and still stay in touch when at work. Sure, they might be able to use a standard single-mode cell phone in the office (assuming cell coverage is good enough), but they wont be connected to the corporate telephone system so they cant access business features like conf erence and transfer, and they need to deal with two separate voicemail systems. And then theres the additional cellular airtime expense that might be racked up if employees are using cell phones as their primary business phones.

This is where a dual-mode handset really makes sense for the business user. The enterprise WiFi network gives them the coverage and reliability they might not get with the cellular network, plus the WiFi network provides access to the corporate telephone switch. Connecting back to the telephone switch could be as simple as using a VoIP protocol such as SIP for an end-to-end IP telephony connection, or it may require a VoIP gateway to interface with a TDM PBX or Centrex service. Either way, the dual-mode handset can operate like the wired business telephones with extension dialing and access to PBX features, and theres no usage or airtime expense since its using the WiFi network.

Most of the utility of a dual-mode handset for an enterprise user comes from having one less device to carry around. Additional capabilities such as broadband Internet access over WiFi in the office, home, or at a hotspot, and extending corporate telephone switch feature access also add value.

Taking Dual-Mode Home
Demand for dual-mode handsets in the residential market is tied more to service offerings than to features. The challenges for implementing WiFi telephony in the enterprise are primarily voice quality, capacity, and feature access; whereas consumers are more interested in cost, ease of use and availability of service. As consumers have embraced cell phones, demand for traditional residential telephone service has diminished. But consumers still want reliable, fixed-cost telephone service at home. A dual-mode handset can meet that need and give wireless and wireline carriers the opportunity to offer new services.

For example, BT recently launched their BT Fusion service in the UK, which was previously known as Project Bluephone. BT Fusion is a service that brings together home cordless and public cellular in a dual-mode handset. The first handset available from BT uses Bluetooth for the home network, but BT has also thrown support behind using WiFi as well. Recognizing that consumers are abandoning traditional home landlines, carriers like BT can offer an all-in-one residential and cellular service plan that gives the consumer what they want one phone that has the same telephone number whether at home or in the car.

The ability to seamlessly handoff calls between the cellular and WiFi networks is probably more important for consumers than for business users, mostly because consumers will expect the same experience no matter which network they are connected to, and ideally they wont even be aware of the fact that they use two very different kinds of wireless networks. Business users will have access to PBX features when using the enterprise WiFi network which may not be available through the cellular network, so it is likely that they will be aware of the different networks and not necessarily expect to be able to roam seamlessly back and forth. Nevertheless, there is a lot of work going into developing inter-network roaming solutions, and these will have implications on both the network and device implementations.

Bringing It All Together
Its a pretty safe bet that dual-mode handsets will proliferate in both enterprise and consumer markets. A few details still need to be worked out for dual-mode phones since WiFi telephony is still in its adolescence. Making it all work together from both a technical and market perspective will require a lot of cooperation between network operators, telecom infrastructure providers and handset developers. But both WiFi and cellular are here to stay, and bringing them together in one device will make mobile communication better for a lot of people in their work and personal lives. In the end however, dual-mode handsets wont be for everyone. There will still be WiFi-only solutions for workplace applications, and likewise, cellular-only handsets will probably never go away.IT

Ben Guderian is vice president of market strategies and industry relations at Spectralink. For more information, please visit the company online at

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