Foreword1 Scope2 References3 Symbols and abbreviations4 Main Concepts5 General Circuit Switched Core Network Domain Architecture6 Call Establishment6 Call Establishment6.1 Basic Mobile Originating Call6.1.1 Forward bearer establishment6.1.2 Backward bearer establishment6.1.3 Originating Call Establishment For Iu Interface on IP6.1.4 Forward bearer establishment with Trace Session Activation6.1.5 Originating Call Establishment for A interface over IP6.2 Basic Mobile Terminating Call6.2.1 Forward bearer establishment6.2.2 Backward bearer establishment6.2.3 Terminating Call Establishment For Iu Interface on IP6.2.4 Terminating Call Establishment For A Interface over IP7 Call Clearing7 Call Clearing7.1 Network Initiated7.2 User Initiated7.3 (G)MSC server Initiated7.4 MGW Initiated7.5 Call Clearing for Iu Interface on IP8 Handover/Relocation8 Handover/Relocation8.1 UMTS to UMTS8.1 UMTS to UMTS8.1.1 Intra-MSC SRNS/SBSS Relocation8.1.2 Basic Inter-MSC SRNS/SBSS Relocation8.1.3 Subsequent Inter-MSC SRNS/SBSS Relocation back to the Anchor MSC8.1.4 Subsequent Inter-MSC SRNS/SBSS Relocation to a third MSC8.1.5 SRNS/SBSS Relocation with Iu on IP8.1.6 Intra-MSC enhanced SRNS Relocation8.1.7 Intra-MSC enhanced SRNS Relocation with Iu on IP8.2 UMTS to GSM8.2 UMTS to GSM8.2.1 Intra-MSC UMTS to GSM Handover8.2.2 Basic Inter-MSC UMTS to GSM Handover8.2.3 Subsequent Inter-MSC UMTS to GSM Handover back to the Anchor MSC8.2.4 Subsequent Inter-MSC UMTS to GSM Handover to a third MSC8.3 GSM to UMTS8.3 GSM to UMTS8.3.1 Intra-MSC GSM to UMTS Handover8.3.2 Basic Inter-MSC GSM to UMTS Handover8.3.3 Subsequent Inter-MSC GSM to UMTS Handover back to the Anchor MSC8.3.4 Subsequent Inter-MSC GSM to UMTS Handover to a third MSC8.3.5 GSM to UMTS Handover with Iu on IP8.4 GSM to GSM8.4.1 Intra-MSC Inter-BSS GSM to GSM Handover8.4.2 Basic Inter-MSC GSM to GSM Handover8.4.3 Subsequent Inter-MSC GSM to GSM Handover back to the Anchor MSC8.4.4 Subsequent GSM to GSM Handover to a third MSC8.4.5 BSS Internal Handover8.5 Handling of GSM Services after UMTS to GSM Handover9 Compatibility Issues10 General (G)MSC server-MGW Procedures11 Identities12 Operational Aspects13 Interactions with Other Services13 Interactions with Other Services13.1 Enhanced Multi-Level Precedence and Pre-emption service (eMLPP)13.2 Call Deflection Service13.3 Line identification Services13.4 Call Forwarding Services13.4.1 Call Forwarding Unconditional (CFU)13.4.2 Call Forwarding on mobile subscriber Busy (CFB)13.4.3 Call Forwarding on No Reply (CFNRy)13.4.4 Call Forwarding on mobile subscriber Not Reachable (CFNRc)13.5 Call Waiting (CW)13.6 Call Hold (CH)13.6 Call Hold (CH)13.6.1 Hold request13.6.2 Retrieval request13.6.3 Setting up another call13.6.4 Alternate from one call to the other13.6.5 Disconnect13.6.6 Failure handling in MSC server13.6.7 Example 113.6.8 Example 213.7 Multiparty (MPTY)13.8 Closed User Group (CUG)13.9 Advice of Charge (AoC)13.10 User-to-User Signalling (UUS)13.11 Call Barring Services13.12 Explicit Call Transfer (ECT)13.13 Completion of Calls to Busy Subscriber (CCBS)13.14 Multiple Subscriber Profile (MSP)13.15 Multicall13.16 Calling Name Presentation (CNAP)13.17 Alternate Speech/Fax13.18 Modification of the Access Bearer13.19 GSM Fax13.20 Voice group call service (VGCS), Voice broadcast service (VBS)13.20.1 Beginning the Voice group call13.20.2 Talker change in Voice group call (1 channel model)13.20.3 Disconnect13.20.4 Failure handling in MSC server13.20.5 Example13.20.6 Voice group call and voice broadcast services with AoIP14 Interactions with Other Network Features and Services14.1 Customised Applications for Mobile network Enhanced Logic (CAMEL)14.2 IST14.3 Operator Determined Barring (ODB)14.4 DTMF14.5 OR14.6 Providing tones or announcements14.7 Global Text Telephony14.8 Emergency Calls14.9 Subscriber and equipment trace14.10 Customized Alerting Tone14.10.1 General15 Tunnelling16 Messages/Procedures and their contents17 Bearer Redirect18 (G)MSC MGW Tandeming19 Timers for bearer independent CS core network20 Multiple IP Realms 12 Operational Aspects 23.2053GPPBearer-independent circuit-switched core networkRelease 17Stage 2TS Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM 12.1 Charging No impacts.