Private Telecommunication Network (PTN); signalling protocol at the S-reference point; circuit mode basic services; English version ETS 300192:1992
Edition 1993-09

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

Private Telecommunication Network (PTN); signalling protocol at the S-reference point; identification supplementary services; English version ETS 300191:1992
Edition 1993-09

Private Telecommunications Network (PTN) - Method for the specification of basic and supplementary services; English version ETS 300387:1994
Edition 1994-11

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

Integrated Services Digital Network (ISDN); Subaddressing (SUB) supplementary service; functional capabilities and information flows; english version ETS 300060:1991
Edition 1992-09

Integrated Services Digital Network (ISDN); Closed User Group (CUG) supplementary service; functional capabilities and information flows; english version ETS 300137:1992
Edition 1992-12