T-Mobile's new service, which will be the first of its kind in the United States, will be a test case for other operators also looking to deploy similar services. Sprint Nextel, through its, is also looking into developing a similar service. And Cingular is testing a service in its labs.
Carriers in Europe, such as Telecom Italia and Orange, have already said they will launch their services later this year, charging between 10 and 15 euros per month for unlimited calling from dual-mode Wi-Fi/cellular phones used in home networks. The business case for consumers in Europe is simple: The dual-mode services are much cheaper than current cell phone and landline rates.
In the United States, where voice minutes are sold in buckets, Wi-Fi/cellular services could be a harder sell. That said, there are some compelling benefits for U.S. consumers. For example, cell phone users will be able to conserve voice minutes while talking on the Wi-Fi network, which could allow them to reduce their usage plans and reduce phone bills. They'll also get access to a higher speed network that allows them to download mobile content, like Web pages, music and games, much faster than they can even from a 3G wireless network.
But analysts, such as Charles Golvin with Forrester Research, say that these services may not catch on with consumers until users see added functionality that they can't get on their regular cellular phones.
"Just like with the voice over IP movement, people will be interested in converged Wi-Fi/cellular services at first based on price," he said. "But eventually it will become more about features."
Tapping the advantages of IP
Specifically, Wi-Fi-based phone services will allow consumers access to a whole slew of IP-enabled features, such as receiving voice mail from a Web portal, or being able to see whether friends on their buddy lists are available for phone calls.
T-Mobile, which is using a standard technologycalled unlicensed mobile access, or UMA, is keeping details of its new service under wraps.
"T-Mobile is interested in the replacement or displacement of landline minutes," a spokeswoman said in an e-mail. "We believe the future will be about leveraging diverse forms of radio access technology for our customers and Unlicensed Mobile Access, we think, is one of the technologies that will help us continue to deliver on that promise.
But Kineto Wireless, one of the companies developing software to enable the service, said a commercial service is expected to launch this month in at least one major city. T-mobile has been testing the service for about a month in the Pacific Northwest, according to several blogs.
Using equipment supplied by T-Mobile, the initial Wi-Fi/cellular service will be limited to home-based Wi-Fi networks that use standard 802.11 Wi-Fi routers from companies such as D-Link or Linksys. The routers will be used to provide the Wi-Fi signal indoors. And users will be able to call anyone over the Wi-Fi home network for a flat fee. When they're outside the Wi-Fi hotspot, the dual-mode phone, which at launch will likely be the Samsung SGH-T709, will automatically switch over to T-Mobile's cellular network.
Eventually, the T-Mobile dual-mode service could be expanded tolocated in airports, cafes and other public areas throughout the country. Once this happens, customers could have even more flexibility in when they get access to the mobile Wi-Fi network.
"I think T-Mobile will migrate to ubiquitous access over time," said Richard Gilbert, CEO of Kineto Wireless. "The service won't work everywhere instantaneously, but this home version is a step in the right direction."