T-Mobile cooks up wi-fi blend on the fly

T-Mobile USA has begun offering a service that allows people to use their mobile phones to talk over T-Mobile's cellular network as well as wi-fi networks.

The new service, called T-Mobile HotSpot @Home, is currently only available in Seattle and is the first of its kind in the US. It is likely to be viewed as a test case by other operators looking to develop similar services.

The benefit of the service for consumers is that it allows them to conserve their mobile phone minutes while they are within one of T-Mobile's hotspots or within range of any other wi-fi hotspot that doesn't require authentication.

The phone automatically detects wi-fi hotspots and uses a technology called unlicensed mobile access, or UMA, to seamlessly switch calls to the wi-fi network from the cellular network. The hand-off is so smooth users don't even know they've been switched to a different network, said a spokesman for T-Mobile.

Just as with VoIP services from companies such as Vonage, T-Mobile callers will be able to talk as long as they like to anyone in the US for a flat monthly fee while they are chatting over wi-fi.

T-Mobile is offering two handsets to be used with the service: the Nokia 6136 and the Samsung T709. Each phone costs $49.99 with a two-year contract or $99 with a one-year contract. While the service works with any standard wi-fi router, T-Mobile is offering a D-Link wi-fi router optimised for the service. The routers are free with a mail-in rebate.

To activate the service, consumers must have a "qualified" T-Mobile voice plan, which starts at $39.99. The wi-fi functionality costs an additional $19.99 per month.

T-Mobile has been testing the service since August in a controlled trial in Seattle with a few hundred users. The company would not say how long it expects the Seattle pilot programme to last or what its plans are for expanding the service.

Marguerite Reardon writes for CNET News.com