T-One

T-One combined landline and mobile phone technologies in one device. The German Telekom marketed since July 31, 2006 under the name of T-One, the TC 300 , a terminal or DUALphone , which is both a VoIP utilizing Wi-Fi - as well as GSM allowed to use cell phone. T-One was offered in two technical variants, T-One DSL and T-One Fixed Line, with the same handset being used in each case.

In contrast to T-Mobile and other competitors who use their products exclusively in the cellular network and offer cheap (landline) tariffs in a limited home zone, T-One combined Internet and GSM telephony in one device. T-One was not officially connected to the T-Mobile products, but the T-Mobile network was used for GSM operation.

In March 2007, the Telekom announced the discontinuation of the offer because of unprofitability, since only "several thousand" customers would have decided on the product. Some customers also complained about ongoing technical breakdowns and immature hardware. The delivery of the end devices did not always go smoothly either.