Content for TS 24.237 Word version: 18.0.0
12 Roles for PS-CS access transfer, Single Radio
12.1 Introduction
12.2 SC UE procedures for PS to CS access transfer, PS to CS SRVCC
12.2A SC UE procedures for PS to CS access transfer, vSRVCC
12.2B SC UE procedures for CS to PS SRVCC
12.3 SCC AS
12.4 MSC server enhanced for ICS
12.4A MSC server assisted mid-call feature
12.5 EATF
12.6 MSC server enhanced for SRVCC using SIP interface
12.7 Access Transfer Control Function (ATCF)
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12 Roles for PS-CS access transfer, Single Radio p. 124
12.1 Introduction p. 124
12.2 SC UE procedures for PS to CS access transfer, PS to CS SRVCC p. 125
12.2.1 General p. 125
12.2.2 ICS-based p. 125
12.2.3 Not based on ICS p. 126
12.2.3A Not based on ICS with MSC Server assisted mid-call feature |R10| p. 126
12.2.3B Call in alerting phase |R10| p. 129
12.2.3B.1 General p. 129
12.2.3B.1A Considerations for MSC server assisted mid-call feature p. 132
12.2.3B.2 Assignment of Transaction Identifiers to the transferred sessions p. 132
12.2.3B.3 Single call in alerting phase or pre-alerting phase p. 133
12.2.3B.3.1 Terminating call in alerting phase p. 133
12.2.3B.3.2 Originating call in alerting phase p. 133
12.2.3B.3.3 PS to CS SRVCC for originating calls in pre-alerting phase |R12| p. 133
12.2.3B.3.4 PS to CS SRVCC for terminating calls in pre-alerting phase |R15| p. 133
12.2.3B.4 Established call with a session in alerting phase or in pre-alerting phase p. 134
12.2.4 Abnormal cases |R9| p. 134
12.2A SC UE procedures for PS to CS access transfer, vSRVCC |R11| p. 135
12.2A.1 General p. 135
12.2A.2 ICS-based p. 136
12.2A.3 Not based on ICS p. 136
12.2A.4 Void
12.2A.5 Call in alerting phase p. 137
12.2A.5A Call in pre-alerting phase |R12| p. 137
12.2A.6 Abnormal cases p. 137
12.2B SC UE procedures for CS to PS SRVCC |R11| p. 137
12.2B.1 Distinction of requests p. 137
12.2B.2 First call transfer p. 138
12.2B.2.1 General p. 138
12.2B.2.2 Transfer of call with active speech media component p. 139
12.2B.2.3 Transfer of call with inactive speech media component p. 139
12.2B.2.4 Transfer of originating call in alerting phase p. 139
12.2B.2.5 Transfer of terminating call in alerting phase p. 139
12.2B.3 Additional call transfer p. 140
12.2B.3.1 General p. 140
12.2B.3.2 Transfer of call with active speech media component p. 141
12.2B.3.3 Transfer of call with inactive speech media component p. 141
12.2B.3.4 Transfer of originating call in alerting phase p. 141
12.2B.3.5 Transfer of terminating call in alerting phase p. 141
12.2B.4 Procedures after calls are transferred p. 142
12.3 SCC AS p. 142
12.3.0 General p. 142
12.3.0A Distinction of requests sent to the SCC AS |R9| p. 142
12.3.0B Determine the transferable session set |R11| p. 143
12.3.1 SCC AS procedures for PS to CS access transfer, PS to CS SRVCC p. 143
12.3.2 SCC AS procedures for PS to CS access transfer with MSC server assisted mid-call feature, PS to CS SRVCC |R10| p. 144
12.3.2.1 General |R11| p. 144
12.3.2.2 Transfer of the first session |R11| p. 145
12.3.2.3 Transfer of an additional session |R11| p. 147
12.3.3 SCC AS procedures for PS to CS SRVCC, abnormal case |R9| p. 149
12.3.3.1 PS to CS SRVCC cancelled by MME/SGSN or failure by UE to transition to CS domain for ongoing session p. 149
12.3.3.1A PS to CS SRVCC cancelled by MME/SGSN or failure by UE to transition to CS domain for session in early dialog state |R10| p. 150
12.3.3.2 P-CSCF releasing the source access leg during PS to CS SRVCC p. 151
12.3.3.3 P-CSCF releasing the source access leg when call is in alerting phase |R10| p. 151
12.3.3.4 PS to CS SRVCC cancelled by MME/SGSN or release of the target access leg for an ongoing session |R10| p. 151
12.3.3.5 PS to CS SRVCC cancelled by MME/SGSN or release of the target access leg for a session in an early dialog phase |R10| p. 152
12.3.4 SCC AS procedures for PS to CS access transfer when call is in alerting phase or pre-alerting phase |R10| p. 154
12.3.4.1 General p. 154
12.3.4.2 SCC AS procedures for PS to CS access transfer for terminating call in alerting phase or pre-alerting phase using PS to CS SRVCC procedure p. 158
12.3.4.3 SCC AS procedures for PS to CS access transfer for originating call in alerting phase or pre-alerting phase using PS to CS SRVCC procedure p. 160
12.3.4.4 SCC AS procedures for PS to CS access transfer of additional call p. 164
12.3.5 SCC AS procedures for PS to CS access transfer: PS to CS SRVCC enhancement using ATCF |R10| p. 169
12.3.6 SCC AS procedures for PS to CS access transfer, vSRVCC |R11| p. 171
12.3.6.0 Determine the transferable session set p. 171
12.3.6.1 General p. 171
12.3.6.2 SCC AS procedures for PS to CS access transfer when call is in alerting phase, vSRVCC p. 172
12.3.6.3 SCC AS procedures for PS to CS access transfer: vSRVCC enhancement using ATCF p. 172
12.3.6.4 SCC AS procedures for vSR-VCC, abnormal case p. 172
12.3.7 SCC AS procedures for handling of SIP OPTIONS request |R11| p. 172
12.3.8 Removal of non-transferred audio media components and superfluous sessions |R11| p. 173
12.3.9 Charging correlation |R11| p. 173
12.3.10 SCC AS procedures for CS to PS SRVCC |R11| p. 173
12.3.10.1 Distinction of requests p. 173
12.3.10.2 First session transfer p. 174
12.3.10.2.1 General p. 174
12.3.10.2.2 Transfer of session with active speech media component p. 175
12.3.10.2.3 Transfer of session with inactive speech media component p. 175
12.3.10.2.4 Transfer of originating session in alerting phase p. 176
12.3.10.2.5 Transfer of terminating alerting session p. 176
12.3.10.3 Additional session transfer p. 177
12.3.10.3.1 General p. 177
12.3.10.3.2 Additional session transfer initiation p. 178
12.3.10.3.3 Transfer of session with inactive speech media component p. 179
12.3.10.3.4 Transfer of originating session in alerting phase p. 180
12.3.10.3.5 Transfer of terminating session in alerting phase p. 180
12.3.10.4 Removal of non-transferred sessions p. 181
12.3.11 SCC AS procedures when the access transfer is completed |R13| p. 181
12.4 MSC server enhanced for ICS |R9| p. 182
12.4.0 MSC server enhanced for ICS supporting PS to CS SRVCC p. 182
12.4.0A MSC server enhanced for ICS procedures for Emergency Session Transfer p. 184
12.4.0B MSC server enhanced for ICS supporting vSRVCC |R11| p. 184
12.4.1 Void
12.4.2 MSC server enhanced for ICS supporting CS to PS SRVCC |R10| p. 185
12.4.2.1 Distinction of requests p. 185
12.4.2.2 General p. 185
12.4.2.3 Transfer of session without MSC server redirecting the speech media component |R11| p. 186
12.4.2.4 Transfer of session with MSC server redirecting the speech media component |R11| p. 186
12.4.2.5 Abnormal cases |R11| p. 187
12.4.3 Abnormal cases |R11| p. 187
12.4A MSC server assisted mid-call feature |R10| p. 188
12.5 EATF |R9| p. 192
12.5.1 EATF procedures for PS to CS session continuity, E-SR-VCC p. 192
12.5.2 EATF procedures for PS to CS SRVCC, abnormal case |R10| p. 193
12.5.2.1 PS to CS SRVCC cancelled by MME/SGSN or release of the target access leg for ongoing emergency session p. 193
12.5.2.2 PS to CS SRVCC cancelled by MME/SGSN or failure by UE to transition to CS domain for ongoing session p. 193
12.5.2.3 P-CSCF releasing the source access leg during PS to CS SRVCC p. 194
12.5.2.4 PS to CS SRVCC cancelled by MME/SGSN or failure by UE to transition to CS domain for session in early dialog state |R15| p. 194
12.5.3 EATF procedures for PS to CS access transfer when emergency session is in alerting phase or pre-alerting phase |R15| p. 195
12.5.3.1 General p. 195
12.5.3.2 EATF procedures for PS to CS access transfer for originating call in alerting phase or pre-alerting phase using PS to CS SRVCC procedure p. 196
12.5.4 Removal of non-transferred audio media components and superfluous sessions |R15| p. 199
12.6 MSC server enhanced for SRVCC using SIP interface |R9| p. 199
12.6.0 General |R14| p. 199
12.6.0A Codec inquiry prior to PS to CS SRVCC access transfer |R14| p. 199
12.6.0B Codec re-negotiation after session transfer |R14| p. 200
12.6.1 Session transfer from MSC server enhanced for SRVCC using SIP interface p. 200
12.6.1.1 Session transfer from MSC server enhanced for SRVCC using SIP interface supporting PS to CS SRVCC |R11| p. 200
12.6.1.2 Session transfer from MSC server enhanced for SRVCC using SIP interface supporting vSRVCC |R11| p. 202
12.6.2 Emergency session transfer from MSC server enhanced for SRVCC using SIP interface p. 203
12.6.3 MSC server enhanced for SRVCC using SIP interface procedures for PS to CS access transfer for calls in alerting phase or pre-alerting phase |R10| p. 203
12.6.4 Abnormal cases |R10| p. 208
12.6.4.1 Permanent response codes p. 208
12.6.4.2 PS to CS SRVCC cancelled by MME/SGSN or failure of the access transfer procedure in the MSC server p. 208
12.6.4.3 Guard timer for the CC CONNECT request elapses |R12| p. 208
12.6.5 Interworking of CC messages and SIP messages when PS to CS SRVCC access transfer is completed |R13| p. 208
12.7 Access Transfer Control Function (ATCF) |R10| p. 209
12.7.1 Distinction of requests p. 209
12.7.2 ATCF procedures for PS to CS access transfer, PS to CS SRVCC p. 210
12.7.2.1 General p. 210
12.7.2.1A Determination of session being transferred when only a held session or only a session in originating pre-alerting phase or a session in alerting phase exist |R14| p. 211
12.7.2.2 Active session transfer p. 212
12.7.2.3 Abnormal procedures p. 216
12.7.2.3.1 P-CSCF releasing the source access leg during PS to CS SRVCC p. 216
12.7.2.3.2 No transferable session exists p. 216
12.7.2.4 Transfer when only a held session or a session in originating pre-alerting phase or a session in alerting phase exist p. 218
12.7.2.5 Transfer of additional session |R13| p. 220
12.7.2.6 Codec inquiry prior to PS to CS SRVCC access transfer |R14| p. 222
12.7.3 ATCF procedures for CS to PS SRVCC |R11| p. 224
