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• CCITT Rec. Q.81.3 (1988) – CALL COMPLETION SUPPLEMENTARY SERVICES – CALL WAITING
• 1 Call waiting
  • 1.1 General
  • 1.2 Description
    • 1.2.1 General description
    • 1.2.2 Qualifications on the applicability to telecommunication services
  • 1.3 Derivation of the functional model for call waiting service
  • 1.4 Information flow diagrams
    • 1.4.1 Call waiting terminology
    • 1.4.2 Call waiting procedures with successful outcome
  • 1.5 SDL diagrams for functional entities
  • 1.6 Functional entity actions
  • 1.7 Allocation of functional entities to physical locations