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TechSpec
  • Foreword
  • 1 Scope
  • 2 References
  • 3 Definitions and abbreviations
  • 4 Service change and fallback for UDI/RDI multimedia
    • 4.1 General Requirements
    • 4.2 Access Call Control Signalling
      • 4.2 Access Call Control Signalling
      • 4.2.1 Mobile originating side - initiation of call setup
      • 4.2.2 Mobile terminating side
      • 4.2.3 Mobile originating side - completion of call setup
      • 4.2.4 User-initiated Service change in the active state
      • 4.2.5 Network-initiated Service change in the active state
    • 4.3 Core Network procedures
      • 4.3 Core Network procedures
      • 4.3.1 Multimedia codec
      • 4.3.2 Originating side - initiation of call setup
      • 4.3.3 Terminating side
      • 4.3.4 Originating side - completion of call setup
      • 4.3.5 Service change during the active state
      • 4.3.6 Interaction with supplementary services
      • 4.3.7 Interactions with CAMEL
      • 4.3.8 Interworking with external networks
      • 4.3.9 User interaction and in-band information
  • 5 Lawful Interception

4.2 Access Call Control Signalling

23.1723GPPRelease 17Stage 2Technical realization of Circuit Switched (CS) multimedia service UDI/RDI fallback and service modificationTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

Using the repeat indicator value "support of service change and fallback", as described in 3GPP TS 24.008 [3], clause 5.3.6, together with two BC-IEs, a multimedia and a speech, it is possible to request a service change and fallback functionality, while still maintaining the backwards compatibility with non-supporting terminals.