We've reviewed Skype phones before that can make calls on both the Skype network and the regular landline, but the RTX Dualphone is the first one that can do both without the need of a PC.
The RTX comes with a charging dock, a base station, and a handset. The base station connects into your ethernet network and your landline, meaning you're free to take the cordless handset anywhere in your house. Even that closet your wife stores her letters from her old lovers in. It's 109.99 ($206), so it's not exactly as the non-standalone phones. T'is the price of progress.
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