HotSpot@Home requires either the Noika 6136, above, or the Samsung SGH-T709. Each is $30 after a rebate.  MATTHEW MILLER wanted to cut the cost of his cellphone plan. He and his wife, Dayna, had regularly exceeded their 2,000-minute-per-month T-Mobile family plan, incurring extra-use charges that reached $60 some months.  With her home business and his daily commute of two and a half hours to his job in Seattle, they decided this year to move to the maximum 3,000-minute plan. They spend another $20 a month for unlimited long-distance calling on their landline.  Mr. Miller, a columnist for Geek.com and ZDNet in his spare time, was therefore not surprised when T-Mobile asked the couple to join an early local test of a service that combines the ubiquity of cellular networks with the flat pricing for unlimited calls available with some Internet-based phone services.  The new service, HotSpot@Home, allows a subscriber to place calls from a mobile phone using cellular and Wi-Fi networks, whether a home wireless network or a hot spot operated by T-Mobile.  In my own testing, I found the service a reasonable first draft of what could become a reliable alternative to both all-cellular networks and an emerging set of Wi-Fi-only phones. The marriage might even save money  for both T-Mobile and its subscribers. Carrying calls over Wi-Fi networks costs the company as little as 20 percent of the expense of calls handled on a cellular network.  All calls originating on a Wi-Fi network to numbers in the United States are included in a monthly fee of $20 for a primary phone and $5 for additional phones in a family plan. The Wi-Fi plan must be coupled with a traditional voice cellular service plan of at least $40 a month.  Although T-Mobile introduced the service in late October, after the tests in which the Millers took part, the company allows subscribers to sign up only in the Seattle-Tacoma region, and only at corporate stores. The service can be used nationwide, however.  The company, based in Bellevue, Wash., declined to comment for attribution for this story, citing its intention to keep interest in the service low until it is nationally available. I tested this service as a walk-up customer at a mall kiosk paying retail price.  The service is designed to pass calls in progress from a Wi-Fi network to the cellular network (or vice versa) when a signal drops in strength, in the same fashion that regular cellphones hand off among many cell towers. To a suitably equipped telephone, Wi-Fi is just another cell tower.  Providing calls over Wi-Fi also has the potential to improve voice quality in often hard-to-serve interior spaces in detached homes and apartment buildings.  While corporations have used telephone handsets or base stations that route calls exclusively over Wi-Fi, those networks require expensive server equipment to ensure call quality, roaming and capacity. Telephones for these networks typically cost at least $300 to $500.  T-Mobile’s service, by contrast, works over networks using much less expensive equipment, including existing home Wi-Fi gateways, as well as a router that T-Mobile offers for free to subscribers after a $50 mail-in rebate. Further, its subscribers bear the cost of the home network broadband connection.  Other Wi-Fi phones have appeared in great variety in recent months, with several models appearing that tie into Skype, the eBay-owned service that dominates free computer-to-computer calling worldwide. For a variety of per-minute and flat-rate fees, Skype also offers calling to and from the public switched-telephone network.  These Wi-Fi-only phones lack cellular radios, and often have difficulty in connecting to Wi-Fi networks that are not completely free and open, or are not operated by the phone’s owner. (Some smartphones feature both cellular and Wi-Fi radios, including several Nokia models sold primarily outside the United States, but carriers that support these phones do not offer hybrid calling plans.) For the T-Mobile service being offered in Seattle, with its dual Wi-Fi and cellular ability, the choice of phones is limited, although more are expected to appear throughout 2007. HotSpot@Home requires either the Nokia 6136 or the Samsung SGH-T709. Both are $30 after a $50 mail-in rebate.  The phones automatically connect to T-Mobile hotspots, and can scan and be configured to connect to any open Wi-Fi network or one secured with a home Wi-Fi security method.  Because the service uses an international standard (Unlicensed Mobile Access) focused on voice, the phones perversely cannot use Wi-Fi networks for data access, and laptop access to T-Mobile hotspots is also not included in the HotSpot@Home plan.
T-Mobile tests a service that offers subscribers in the Seattle area a chance to call more for less.