| Заглавие на английском языке | Integrated Services Digital Network (ISDN) - Direct Dialling In (DDI) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol - Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT) proforma specification for the user; English version ETS 300064-4:1997 |