(Telecompaper) Deutsche Telekom and Softbank have completed the merger of their US mobile operators T-Mobile and Sprint. T-Mobile's takeover of its smaller rival Sprint is expected to strengthen its position as challenger to the top US mobile operators AT&T and Verizon. The company will be lead by former T-Mobile COO Mike Sievert, who takes over from John Legere as CEO from 01 April, when the new T-Mobile officially launches.