VoIP Central is reporting that T-Mobile is working on a new service that will allow customers to use one phone that will switch between cell and WiFi networks, T-Mobile At Home (TAH).
T-Mobile’s product testing company, Centercode, has started tests on their upcoming TAH service. TAH is a wireless router-type device that broadcasts GSM and does VoIP through your broadband connection. Using T-Mobile, customers will be able to use their mobile phones as a cell phone on T-Mobile's network, but will be able to switch to WiFi when a network is available. Calls would then be routed over VoIP rather than T-Mobile's cellular network, allowing customers to make and receive phone calls from the same phone number.
The benefits would be better call quality, reduced load on the cell networks, and probably most important to many consumers, preserving precious call plan minutes. It is anticipated that T-Mobile will charge a monthly fee for the service, which is expected to be lower than current landline costs.
Additionally, there might be new services involved such as the ability to retrieve voice-mail messages over the Web and seeing which of your phone contacts are 'online' and available to receive phone calls, similar to Skype.
T-Mobile is currently signing up customers only over e-mail and having them reply via e-mail. People who call up customer service or go to T-Mobile stores cannot sign up.
With T-mobile At Home and the included Samsung dual-mode phone (WiFi + Cellular), you can switch back and forth between the cellular network and any WiFi access point.