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Integrated Services Digital Network (ISDN) - Digital Subscriber Signalling System No. one (DSS1) protocol - Signalling network layer for circuit-mode basic call control - Part 2: Specification and Description Language (SDL) diagrams
Digital cellular telecommunications system (Phase 2+) - Mobile radio interface layer 3 specification - Radio Resource Control Protocol (GSM 04.18 version 8.4.1 Release 1999)