The Siemens DCO (digital central office) electronic telephone switch was introduced in 1977 by Stromberg-Carlson, having been conceived by its new president, Leonard A. Muller, an ex IBM senior executive who infused Stromberg with his new digital awareness learned in IBM.
In a revolutionary project headed by lead engineer and chief of project development, Mick Richmond, the Stromberg-Carlson DCO was one of the first digital class 5 telephone switches ever installed in the World's telecommunications network, Muller was quick to recognize the value digital technology brought to the science of electronic switching and commenced a major digital development program shortly after taking over management of Stromberg in 1974.
Stromberg-Carlson put their switch into service in July 1977 in a telephone exchange in Richmond Hill, Georgia.
In the next few years Siemens slowly phased out the DCO as a line side central office switch.
In 2006 the entire Siemens DCO line was sold to Genband, originally a VoIP gateway / softswitch company from Texas, USA.