After a year and a half of testing in tech-y places like Seattle, T-Mobile USA Inc. has officially taken its Wi-Fi-cellular roaming service, Hotspot@Home, to the average American consumer. It leaves industry-watchers wondering, will this be a bellwether in the ongoing phenomenon of wireline displacement?

     Available nationwide as of today, the UMA-based service allows subscribers to roam between T-Mobile’s cellular GSM network and open, unlocked Wi-Fi networks (such as one you might set up at home, hence the name). The service launches with two $50 handsets — the Nokia 6086 and the Samsung t409. Neither are smart phones, but then, the service is targeted to consumer voice users who want the convenience of one untethered handset, but better indoor coverage than you would get with existing cellular technology.

     Calls, long-distance or otherwise, originating on a Wi-Fi network are unlimited and included in the HotSpot@Home service plan, even if the calls roam over to cellular. The Wi-Fi plan costs $19.99 per month for individuals and $29.99 for families; for now, there is a $10 discount on pricing, bringing it to $9.99 and $19.99, respectively. Even without the discount, it’s still cheaper than a flat-rate landline from the RBOC or cablecos.

     Subscribers also need a cellular T-Mobile plan, and calls originating on the cellular network and continuing on the Wi-Fi network are billed as cellular calls.

     With the two service plans in place, one of the dual-mode handsets and a Wi-Fi router, the average Joe will be ready to go, because no configuration is necessary. And, the phones seamlessly carry calls back and forth between networks. As for quality, initial reports vary from “spotty” to “pretty good,” with a few notices of dropped calls during the handover between networks. Five-nines reliability is unlikely, but as a cost-conscious mass-market offer aimed at gaining ground in the home phone market vis a vis ILECs, cablecos and VoIP providers, it bears watching.