T-Mobile has always looked a bit under-nourished and anemic next to its three sturdier sisters--Cingular, Verizon and Sprint Nextel. Still, these have been two good weeks for T-Mobile. Last week, both Paul Taylor of the Financial Times and Walter Mossberg of the Wall Street Journal offered rave reviews of the BlackBerry 8100, aka BlackBerry Pearl, RIM's latest offering. The Pearl, as is the case with its predecessors, offers a great e-mail feature, but adds to it video, camera, and music functions. The Pearl will give Palm's Treo 750, Motorola's Q, and Nokia's E61/E62 a run for their money, and then some. T-Mobile is currently the only company offering it, and the device will run on the T-Mobile GSM/GPRS/Edge wireless network.

T-Mobile is not stopping there. Now we hear that the company is readying a dual mobile phone which customers will be able to use on cellular and WiFi networks. The company will roll out the service in phases with the first phase seeing customers using the dual phone over the company's GSM cellular networks and using VoIP service through home-based WiFi networks. At a later phase the company will allow customers to use the VoIP capabilities in its 8,000 hot spots.

Now, T-Mobile's small size relative to the other wireless providers gives it an extra incentive to offer the dual service. Most Americans pay a flat fee for a certain number of monthly wireless minutes (in the case of Cingular, the unused monthly minutes roll over to the next month), and thus have less of an incentive to replace traditional cell service with VoIP. T-Mobile, however, owns less spectrum than the other providers and would benefit from its customers moving over to VoIP in the process freeing up some of its limited spectrum so that it would have more capacity on its existing cellular network for both more customers and high-bandwidth applications such as mobile music and video.

For more on T-Mobile's plans:
- see Geoff Duncan's Digital Trends report
- and Susan Campbell's TMCnet report

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