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• CCITT Rec. Q.400 Sup.6 (11/1988) – LINE SIGNALLING (DIGITAL VERSION) WITH METERING
  • 1 Introduction
  • 2 Signal codes
  • 3 Choice of meter codes
  • 4 Clauses for exchange line signalling equipment
    • 4.1 Normal operating conditions
    • 4.2 Actions appropriate to various signalling conditions
  • 5 Protection against the effects of faulty transmission
    • 5.1 Introduction
    • 5.2 Incoming switching equipment
    • 5.3 Outgoing switching equipment
  • 6 Bothway working