Private Telecommunication Network (PTN); signalling at the S-reference point; generic feature key management protocol for the control of supplementary services; English version ETS 300240:1993
Edition 1993-12

Private Telecommunication Network (PTN); signalling at the S-reference point; generic keypad protocol for the support of supplementary services; English version ETS 300190:1992
Edition 1993-09

Integrated Services Digital Network (ISDN); user-network interface layer 3; specification for basic call control; english version ETS 300102-1:1990
Edition 1992-02

Integrated Services Digital Network (ISDN); attachment requirements for terminal equipment to connect to an ISDN using ISDN basic access; layer 3 aspects; english version ETS 300104:1991
Edition 1992-05

Integrated Services Digital Network (ISDN); user-network interface data link layer specification; application of CCITT recommendations Q.920/I.440 and Q.921/I.441; english version ETS 300125:1991
Edition 1992-05