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• CCITT Rec. Q.712 (11/1988) – DEFINITION AND FUNCTION OF SCCP MESSAGES
• 1 Signalling connection control part messages
  • 1.1 Connection Confirm (CC)
  • 1.2 Connection Request (CR)
  • 1.3 Connection Refused (CREF)
  • 1.4 Data Acknowledgement (AK)
  • 1.5 Data Form 1 (DT1)
  • 1.6 Data Form 2 (DT2)
  • 1.7 Expedited Data (ED)
  • 1.8 Expedited Data Acknowledgement (EA)
  • 1.9 Inactivity Test (IT)
  • 1.10 Protocol Data Unit Error (ERR)
  • 1.11 Released (RLSD)
  • 1.12 Release Complete (RLC)
  • 1.13 Reset Confirm (RSC)
  • 1.14 Reset Request (RSR)
  • 1.15 Subsystem-Allowed (SSA)
  • 1.16 Subsystem-Out-of-Service-Grant (SOG)
  • 1.17 Subsystem-Out-of-Service-Request (SOR)
  • 1.18 Subsystem-Prohibited (SSP)
  • 1.19 Subsystem-Status-Test (SST)
  • 1.20 Unitdata (UDT)
  • 1.21 Unitdata Service (UDTS)
• 2 SCCP parameter
  • 2.1 affected point code
  • 2.2 affected subsystem number
  • 2.3 calling/called party address
  • 2.4 credit
  • 2.5 data
  • 2.6 diagnostic
  • 2.7 error cause
  • 2.8 end of optional parameters
  • 2.9 local reference number (source/destination)
  • 2.10 protocol class
  • 2.11 receive sequence number
  • 2.12 refusal cause
  • 2.13 release cause
  • 2.14 reset cause
  • 2.15 return cause
  • 2.16 segmenting/reassembling
  • 2.17 sequencing/segmenting
  • 2.18 subsystem multiplicity indicator
• 3 Inclusion of fields in the messages