ETSI EN 301 065-4 English Printed Edition English PDF Final draft Version 1.2.1Integrated Services Digital network (ISDN); Digital Subscriber Signalling System No. one (DSS1) protocol; Completion of Calls on No Reply (CCNR) supplementary service; Part 4: Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)

standard published 12/01/2001 by European Telecommunications Standards Institute