Foreword1 Scope2 References3 Definitions and abbreviations4 Customized Alerting Tones (CAT)A.1 Scope of signalling flowsA.2 VoidA.3 CAT forking model signalling flowsA.4 CAT early session model signalling flowsA.5 CAT Gateway model signalling flowsA.5.1 IntroductionA.5.2 CAT when UE#1 and UE#2 have resources availableA.5.2A CAT using reINVITE request when UE#1 and UE#2 have resources availableA.5.3 CAT when UE#1 does not have required resources available while UE#2 has resources availableA.5.3A CAT using reINVITE request when UE#1 does not have required resources available while UE#2 has resources availableA.5.4 CAT when UE#1 has resources available while UE#2 does not have required resources availableA.5.4A CAT using reINVITE request when UE#1 has resources available while UE#2 does not have required resources availableA.5.5 CAT diverting for CFNR using reINVITE request when UE#1, UE#2 and UE#3 have resources availableA.5.6 CAT diverting for CFUA.5.6.1 GeneralA.5.6.2 Gateway model CAT diverting for CFU when UE#1, UE#2 and UE#3 have resources availableA.5.7 CAT when both UE#1 and UE#2 do not have required resources availableA.5.8 CAT with different media types during one SIP session when both UE#1 and UE#2 do not have required resources availableA.6 Interworking with CS domain A.2 Void 24.1823GPPIP Multimedia Subsystem (IMS) Customized Alerting Tones (CAT)Protocol specificationRelease 17TS Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM