EntityQ668960· pop 5· linked from 12 articlesOperation SilverSign in to saveoperation in Allied-occupied Austria which ran from 1949 to 1955 that covertly tapped into the landline communications of the Soviet Army headquarters in ViennaConnectionsAustriaCountryLondonCityBerlinEntityWorld War IIConceptViennaEntityInternational Standard Book NumberEntityCentral Intelligence AgencyEntitysovereigntyEntityKGBEntitySecret Intelligence ServiceEntitySchwechatEntityAllied-occupied AustriaEntitytweedEntitySoviet ArmyEntitylandline telephoneEntitySoviet occupation zone of GermanyEntityGeorge BlakeEntityOperation GoldEntityDollis HillEntityPost Office LimitedEntityCategoriesAustria articles missing geocoordinate dataClandestine operationsCold War history of the United KingdomSoviet Union–United Kingdom relationsTunnels in AustriaUnited Kingdom intelligence operations