EWSD (Elektronisches Wählsystem Digital in German, Electronic Digital Switching System/Electronic World Switch Digital in English) is one of the most widely installed telephone exchange systems in the world. EWSD can work as a local or tandem switch or combined local/tandem, and for landline or mobile phones. It is manufactured by Siemens AG, who claims that EWSD switches perform switching for over 160 million subscriber lines in more than 100 countries.
DeTeWe bought its first EWSD under license in 1985 for remote switching. Bosch built its first EWSD as a local exchange in 1986. Deutsche Telekom, formerly Deutsche Bundespost, the largest German telephone company, uses EWSD and System 12 (Alcatel), the former more than the latter.
In 2007, Nokia Corporation and Siemens AG formed the new company Nokia Siemens Networks, and responsibility of further development and shipments of the EWSD system is dependent on this new company.