Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol - Closed User Group (CUG) supplementary service - Part 1: Protocol specification (ITU-T Q.2955.1:1996, modified) (Endorsement of the English version ETS 300770-1:1998 as German standard)
Edition 2000-01

Integrated Services Digital Network (ISDN) - Closed User Group (CUG) supplementary service; Digital Subscriber Signalling System No. one (DSS1) protocol - Part 1: Protocol specification (Endorsement of the English version EN 300138-1 V 1.3.4 (1998-06) as German standard)
Edition 2000-01

Integrated Services Digital Network (ISDN) - Closed User Group (CUG) supplementary service - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 2: Protocol Implementation Conformance Statement (PICS) proforma specification (Endorsement of the English version EN 300138-2 V 1.3.4 (1998-06) as German standard)
Edition 2000-01

Integrated Services Digital Network (ISDN) - Closed User Group (CUG) supplementary service - Digital Subscriber Signalling System No. one (DSS1) protocol - Part 3: Test Suite Structure and Test Purposes (TSS&TP) specification for the user (Endorsement of the English version EN 300138-3 V 1.3.4 (1998-06) as German standard)
Edition 2000-01

Broadband Integrated Services Digital Network (B-ISDN) - Digital Subscriber Signalling System No. two (DSS2) protocol; closed User Group (CUG) supplementary service - Part 2: Protocol Implementation Conformance Statement (PICS) proforma specification (Endorsement of the English version ETS 300770-2:1998 as German standard)
Edition 2000-01

Integrated Services Digital Network (ISDN) - Closed User Group (CUG) 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 (Endorsement of the English version EN 300138-4 V 1.4.3 (2000-05) as German standard)
Edition 2000-10