PRETS 300 052-1990 Integrated Services Digital Network (ISDN): Multiple Subscriber Number (MSN) Supplementary Service Digital Subscriber Signaling One (DSS1) Protocol (T/S 46-33B)
1991PRETS 300 052-1991 Integriertes dienstleistungsdigitales Netzwerk (ISDN); Multiple Subscriber Number (MSN) Supplementary Service Digital Subscriber Signaling System No. One (DSS1)-Protokoll
1990PRETS 300 052-1990 Integrated Services Digital Network (ISDN): Multiple Subscriber Number (MSN) Supplementary Service Digital Subscriber Signaling One (DSS1) Protocol (T/S 46-33B)