ETSI EN 300 369-3 English Printed Edition English PDF Final draft Version 1.3.1Integrated Services Digital Network (ISDN); Explicit Call Transfer (ECT) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol; Part 3: Test Suite Structure and Test Purposes (TSS&TP) specification for the user

standard published 01/01/2002 by European Telecommunications Standards Institute