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There was a time when high costs ensured that cell phones were only used by people out of the range of a fixed-line phone.
These days, however, with wireless calls averaging just a few cents a minute, mobile conversations occur nearly as often from the comfort of the home as from the road. For many, the only tethers to the wired world are the twin fears of dropped calls and running out of minutes.
Now, mobile-phone manufacturers are looking to add another feature that could prompt customers to ditch their land lines. A new generation of handsets will allow people to make ultra-low-cost calls using their cellular handsets over wireless broadband networks.
Developers of software for so-called dual-mode phones, which can switch automatically between traditional cellular and wireless broadband networks for voice calls, are aggressively pushing the technology to carriers. So far, no U.S. carrier has announced plans to deploy a dual-mode Wi-Fi phone.
However, industry analysts say research indicates that there would be sizeable demand from cell-phone customers should such devices hit the market. A recent report by one firm, ABI Research, predicted that by the end of this decade there will be more than 100 million handsets in the world that can connect to either a cellular network or a Wi-Fi network for voice calls.
"Cost is a real factor in all of this. If you're in a Wi-Fi setting on a cell phone, it's fast and it's cheap," said Neil Strother, senior analyst at In-Stat, who doesn't expect the technology to gain a large following for another year or two. Among early adopters, however, Strother expects dual-mode phones will sell well. According to a survey of cell-phone users released in April, In-Stat found that more than 4 in 10 respondents were very or extremely interested in buying a wireless phone with built-in Wi-Fi for voice and data.
Presently, handsets for sale in the United States with Wi-Fi capability -- such as HP's H6315 and Siemens' SX66 PDA phones -- use the wireless broadband capability for data rather than voice. Although a person could theoretically download a program for making calls over the internet, users of Wi-Fi-enabled smartphones generally rely on the cellular network for voice communication.
Steven Shaw, director of marketing for Kineto Wireless, believes smartphones equipped to transmit both voice and data over Wi-Fi networks will draw more buyers than data-only handsets. Shaw's viewpoint is not without financial motivation, however, since Kineto's business involves selling technology for switching between cellular and Wi-Fi networks based on a standard called Unlicensed Mobile Access, or UMA.
"For this to take off, you have to have a pretty robust cellular market, but you also have to have a broadband market," Shaw said. He believes dual-mode services will likely succeed first in Europe, where cell-phone calls are more expensive than in the United States. However, he doesn't rule out the possibility of a U.S. carrier stepping up to the plate first.
But the largest domestic carriers have been hesitant to embrace the technology.
Cingular Wireless, which has been selling Siemens' Wi-Fi-enabled PDA since January, says it sees strong demand for data services using the wireless broadband capability. However, the carrier does not currently have a plan for rolling out Wi-Fi voice services.
Sprint spokesman Bill Elliott said the company is "heavily in the process of evaluating" the feasibility of phones that work on both Wi-Fi and its mobile voice network. However, the company is not engaged today in any trials of dual-mode Wi-Fi phones.
Verizon Wireless, meanwhile, has shied away from Wi-Fi phones, opting to focus instead on a proprietary service, BroadbandAccess, that lets users maintain a mobile, high-speed internet connection across an urban area.
"The mobility factor brings a lot more value to the end user than what Wi-Fi has to offer right now," said Ken Muche, a spokesman for Verizon. "You're not going to be tied down to a coffee shop or the lobby of a hotel."
Lack of enthusiasm from carriers hasn't stopped proponents of Wi-Fi phones from issuing optimistic projections.
Philip Solis, senior analyst at ABI Research, expects to see demand from businesses, especially retail and warehouse operations, for Wi-Fi-only phones that don't access a cellular network but can be used in a building with broadband access.
As for dual-mode Wi-Fi phones, Solis believes much of the interest will come from people who want to talk on their cell phones at home or the office without wasting more-expensive wireless minutes. Besides being cheaper, Wi-Fi calls won't be as prone to static or disconnection.
"Some people just can't get a good cell-phone connection in their house," Solis said. "If they could get a good, strong Wi-Fi connection, that would be great."
Under optimal conditions, cell-phone users wouldn't even notice when their call is being passed to a Wi-Fi network, said Biju Nair, general manager of the wireless product group at Pctel, which makes software for handling such switchovers.
"If you're riding a train to work, on the train you'll be using the cellular network. But as you get near your office, we'll switch you automatically to the Wi-Fi network," Nair said.
According to Shaw, adding Wi-Fi capability doesn't require much expense. He estimates it would cost a manufacturer only about $5 to add a Wi-Fi radio to a phone.
But the work doesn't end there. If they decide to move forward with the technology, carriers will have to invest substantial amounts to upgrade their networks to switch mobile calls to Wi-Fi networks, said Sprint's Elliott.
Seamless switching between Wi-Fi and cellular calls, he said, may sound compelling, but it is not the sort of undertaking for which a company can "think of the idea and have it out in a month."
