DIN ETS 300054:1992-09 Integrated Services Digital Network (ISDN); Terminal Portability (TP) supplementary service; functional capabilities and information flows; english version ETS 300054:1991
1992DIN ETS 300054:1992-09 Integrated Services Digital Network (ISDN); Terminal Portability (TP) supplementary service; functional capabilities and information flows; english version ETS 300054:1991
1992DIN ETS 300054:1992 Integrated Services Digital Network (ISDN); Terminal Portability (TP) supplementary service; functional capabilities and information flows; english version ETS 300054:1991