One reason consumers are reluctant to cancel their land-line phone service is because of poor wireless coverage in their homes.

T-Mobile USA thinks it has solved that — at least in Seattle.

This week, the Bellevue-based company has started selling a new service that allows people to make and receive unlimited phone calls on a Wi-Fi network at home. The service also works at T-Mobile HotSpot locations, many of which are found in airports and at Starbucks.

For now, T-Mobile HotSpot@Home is available only through a pilot program in the greater Seattle area. Customers can purchase it through 24 T-Mobile retail stores from Bellingham to Issaquah to Tacoma.

The new service is being sold as an alternative to a land-line phone. In fact, T-Mobile is using the phrase "the only phone you need" to market it.

T-Mobile Chief Executive Robert Dotson said his company is in a unique position to encourage people to drop their land lines because his company is not associated with a U.S. land-line carrier, such as Verizon Wireless, which is jointly owned by Verizon Communications and Vodafone, and Cingular Wireless, owned by AT&T and BellSouth.

Dotson said getting customers to drop their land lines is an obvious way to gain subscribers at a time when the pool of people in the U.S. who don't have cellphone is diminishing.

"Land-line displacement is the next logical place — the most brain-dead place to go," Dotson said in earlier this month. "There's a lot of discussion of what do you do when penetration rates [of cellphones] hit 80 percent. But let's look at the full telephony dollar that's being spent today. If the behavior exists today, how can we get it on a mobile device?"

Customers who want the service must buy a new cellphone and sign up for a new rate plan. There are two phones to pick from — the Samsung t709 and Nokia 6136; both are $50 after rebates with a two-year contract.

The service costs an additional $20 a month on top of a monthly plan of $40 or more.

To use it, customers must buy a wireless router from T-Mobile and connect it to either a DSL or cable broadband connection at home. The router is free after a rebate.

The technology that T-Mobile USA is using is based on Unlicensed Mobile Access (UMA), which allows calls to be transferred from a cellphone network to Wi-Fi.

T-Mobile spokesman Peter Dobrow said the company chose to roll out the pilot program in Seattle because people are cutting the cord at a higher rate here than most cities, and because it is a convenient location for T-Mobile to monitor the pilot.

In a recent study by research firm Telephia, Seattle ranked seventh most active when it came to dropping land lines, with nearly 170,000 households — or 13.2 percent of all area households — declaring themselves as wireless only. Detroit had the most wireless-only households, followed by Minneapolis, Tampa, Fla., Atlanta, Washington and Phoenix.

T-Mobile provides information on the service at www.theonlyphoneyouneed.com.

Tricia Duryee: 206-464-3283 or tduryee@seattletimes.com