Despite recent media reports, Fischer, a spokesman at the Siemens division Information and Communication Networks, said that both units "are being reintegrated into the group's US operations; they are not being sold."
Last week, Siemens sold Internet routing company Unisphere Networks to Juniper Networks. Since then, analysts have speculated that the German electronics and telecommunication giant would shed other loss-making units in the US.
"There's been plenty of speculation over the past few days by analysts and others that we will be selling more of our US business units," Fischer said. "We are reorganizing, not selling."
According to Fischer, the independent optical-networking subsidiary Optisphere Networks and Efficient Networks are being integrated into the Siemens network holding company, Siemens Information and Information Networks.
Unisphere, which achieved a foothold in the highly competitive US long-haul transmission market, is now focusing on the metropolitan market. Both sectors, however, have been hit hard by the economic downturn and the exodus of service providers.
Thomas Ganswindt, chairman of the ICN division, said that after the Unisphere divestment Siemens will remain focused on voice-centric technologies, such as soft switches and voice gateways, as well as broadband access and optical networking.