ETSI TS 124 008 V15.8.0 (2020-01)

TECHNICAL SPECIFICATION
Digital cellular telecommunications system (Phase 2+) (GSM);
Universal Mobile Telecommunications System (UMTS);
LTE;
5G;
Mobile radio interface Layer 3 specification;
Core network protocols;
Stage 3
(3GPP TS 24.008 version 15.8.0 Release 15)

3GPP TS 24.008 version 15.8.0 Release 15 1 ETSI TS 124 008 V15.8.0 (2020-01)

Reference
RTS/TSGC-0124008vf80
Keywords
5G,GSM,LTE,UMTS
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DECT™, PLUGTESTS™, UMTS™ and the ETSI logo are trademarks of ETSI registered for the benefit of its Members.

3GPP™ and LTE™ are trademarks of ETSI registered for the benefit of its Members and
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ETSI
3GPP TS 24.008 version 15.8.0 Release 15 2 ETSI TS 124 008 V15.8.0 (2020-01)
Intellectual Property Rights
Essential patents
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Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
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"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
3GPP TS 24.008 version 15.8.0 Release 15 3 ETSI TS 124 008 V15.8.0 (2020-01)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 28
Introduction . 28
1 Scope . 29
1.1 Scope of the Technical Specification . 29
1.2 Application to the interface structures . 29
1.3 Structure of layer 3 procedures . 29
1.4 Test procedures . 30
1.5 Use of logical channels in A/Gb mode . 30
1.6 Overview of control procedures . 30
1.6.1 List of procedures . 30
1.7 Applicability of implementations . 32
1.7.1 Voice Group Call Service (VGCS) and Voice Broadcast Service (VBS). 32
1.7.2 General Packet Radio Service (GPRS) . 32
1.7.2.1 Packet services in GSM (A/Gb mode only) . 32
1.7.2.2 Packet services in Iu mode (Iu mode only) . 33
1.8 Handling of NAS signalling low priority indication . 33
1.9 Restrictions . 34
2 References . 34
2.1 Definitions and abbreviations . 41
2.1.1 Random values . 41
2.1.2 Vocabulary . 41
3 Radio Resource management procedures . 47
4 Elementary procedures for Mobility Management . 47
4.1 General . 47
4.1.1 MM and GMM procedures . 47
4.1.1.1 Types of MM and GMM procedures . 47
4.1.1.1.1 Integrity Checking of Signalling Messages in the Mobile Station (Iu mode only) . 49
4.1.1.1.1a Integrity protection for emergency call (Iu mode only) . 51
4.1.1.2 MM-GMM co-ordination for GPRS MS's . 51
4.1.1.2.1 GPRS MS operating in mode A or B in a network that operates in mode I . 51
4.1.1.2.2 GPRS MS operating in mode A or B in a network that operates in mode II . 52
4.1.1.2A Coordination between GMM and EMM . 53
4.1.1.3 Core Network System Information for MM (Iu mode only) . 53
4.1.1.4 Core Network System Information for GMM (Iu mode only) . 53
4.1.1.4.1 General . 53
4.1.1.4.2 Control of Network Mode of Operation I . 53
4.1.1.5 Access class control . 54
4.1.1.6 Specific requirements for MS configured to use timer T3245 . 54
4.1.1.6A Specific requirements for the MS when receiving non-integrity protected reject messages . 55
4.1.1.7 Handling of NAS level mobility management congestion control . 60
4.1.1.8 Handling of security related parameters at switch on and switch off . 61
4.1.1.9 Equivalent PLMNs list . 62
4.1.1.10 Dedicated core network . 62
4.1.2 MM sublayer states . 62
4.1.2.1 MM sublayer states in the mobile station . 62
4.1.2.1.1 Main states . 62
4.1.2.1.2 Substates of the MM IDLE state . 66
4.1.2.2 The update Status . 68
4.1.2.3 MM sublayer states on the network side . 68
4.1.3 GPRS mobility management (GMM) sublayer states . 70
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4.1.3.1 GMM states in the MS . 70
4.1.3.1.1 Main states . 70
4.1.3.1.2 Substates of state GMM-DEREGISTERED. 71
4.1.3.1.3 Substates of state GMM-REGISTERED . 71
4.1.3.2 GPRS update status . 74
4.1.3.3 GMM mobility management states on the network side . 74
4.1.3.3.1 Main States . 75
4.1.3.3.2 Substates of state GMM-REGISTERED . 75
4.2 Behaviour of the MS in MM Idle state, GMM-DEREGISTERED state and GMM-REGISTERED state . 76
4.2.1 Primary Service State selection . 76
4.2.1.1 Selection of the Service State after Power On. 76
4.2.1.2 Other Cases . 77
4.2.2 Detailed Description of the MS behaviour in MM IDLE State. . 77
4.2.2.1 Service State, NORMAL SERVICE . 77
4.2.2.2 Service State, ATTEMPTING TO UPDATE . 78
4.2.2.3 Service State, LIMITED SERVICE . 78
4.2.2.4 Service State, NO IMSI . 79
4.2.2.5 Service State, SEARCH FOR PLMN, NORMAL SERVICE . 79
4.2.2.6 Service State, SEARCH FOR PLMN . 80
4.2.2.7 Service State, RECEIVING GROUP CALL (NORMAL SERVICE) . 80
4.2.2.8 Service State, RECEIVING GROUP CALL (LIMITED SERVICE) . 80
4.2.2.9 Service State, eCALL INACTIVE . 81
4.2.3 Service state when back to state MM IDLE from another state . 81
4.2.4 Behaviour in state GMM-DEREGISTERED. 82
4.2.4.1 Primary substate selection . 82
4.2.4.1.1 Selection of the substate after power on or enabling the MS's GPRS capability . 82
4.2.4.1.2 Other Cases . 83
4.2.4.2 Detailed description of the MS behaviour in state GMM-DEREGISTERED . 83
4.2.4.2.1 Substate, NORMAL-SERVICE . 83
4.2.4.2.2 Substate, ATTEMPTING-TO-ATTACH . 83
4.2.4.2.3 Substate, LIMITED-SERVICE . 84
4.2.4.2.4 Substate, NO-IMSI . 84
4.2.4.2.5 Substate, NO-CELL . 84
4.2.4.2.6 Substate, PLMN-SEARCH . 84
4.2.4.2.7 Substate, ATTACH-NEEDED . 84
4.2.4.2.8 Substate, SUSPENDED (A/Gb mode only) . 84
4.2.4.3 Substate when back to state GMM-DEREGISTERED from another GMM state . 84
4.2.5 Behaviour in state GMM-REGISTERED . 85
4.2.5.1 Detailed description of the MS behaviour in state GMM-REGISTERED . 85
4.2.5.1.1 Substate, NORMAL-SERVICE . 85
4.2.5.1.2 Substate, SUSPENDED (A/Gb mode only) . 85
4.2.5.1.3 Substate, UPDATE-NEEDED . 86
4.2.5.1.4 Substate, ATTEMPTING-TO-UPDATE . 86
4.2.5.1.5 Substate, NO-CELL-AVAILABLE . 86
4.2.5.1.6 Substate, LIMITED-SERVICE . 87
4.2.5.1.7 Substate, ATTEMPTING-TO-UPDATE-MM . 87
4.2.5.1.8 Substate, PLMN-SEARCH . 87
4.3 MM common procedures . 87
4.3.1 TMSI reallocation procedure . 87
4.3.1.0 General . 87
4.3.1.1 TMSI reallocation initiation by the network . 88
4.3.1.2 TMSI reallocation completion by the mobile station . 88
4.3.1.3 TMSI reallocation completion in the network. 88
4.3.1.4 Abnormal cases in the mobile station. 88
4.3.1.5 Abnormal cases on the network side . 89
4.3.2 Authentication procedure . 89
4.3.2a Authentication procedure used for a UMTS authentication challenge . 89
4.3.2b Authentication Procedure used for a GSM authentication challenge . 90
4.3.2.1 Authentication request by the network . 90
4.3.2.2 Authentication response by the mobile station . 90
4.3.2.3 Authentication processing in the network . 91
4.3.2.3a 128-bit circuit-switched GSM ciphering key . 91
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4.3.2.4 Ciphering key sequence number . 91
4.3.2.5 Authentication not accepted by the network . 92
4.3.2.5.1 Authentication not accepted by the MS . 93
4.3.2.6 Abnormal cases . 93
4.3.2.6.1 MS behaviour towards a network that has failed the authentication procedure. 96
4.3.2.7 Handling of keys at intersystem change from Iu mode to A/Gb mode . 96
4.3.2.7a Use of established security contexts . 97
4.3.2.8 Handling of keys at intersystem change from A/Gb mode to Iu mode . 98
4.3.2.9 Void. 99
4.3.2.10 Derivation of keys at SRVCC or vSRVCC handover from S1 mode . 99
4.3.2.10.0 General . 99
4.3.2.10.1 PDN connection with integrity protection . 99
4.3.2.10.2 PDN connection without integrity protection . 99
4.3.2.11 Derivation of keys at SRVCC handover from Iu mode to Iu mode . 99
4.3.2.11.1 PDN connection with integrity protection . 99
4.3.2.11.2 PDN connection without integrity protection . 100
4.3.2.12 Derivation of keys at SRVCC handover from Iu mode to A/Gb mode . 101
4.3.2.12.1 PDN connection with integrity protection . 101
4.3.2.12.2 PDN connection without integrity protection . 102
4.3.2.13 Derivation of keys at CS to PS SRVCC handover from A/Gb mode to Iu mode . 102
4.3.3 Identification procedure . 104
4.3.3.0 General . 104
4.3.3.1 Identity request by the network . 104
4.3.3.2 Identification response by the mobile station . 104
4.3.3.3 Abnormal cases in the mobile station. 104
4.3.3.4 Abnormal cases on the network side . 104
4.3.4 IMSI detach procedure . 105
4.3.4.0 General . 105
4.3.4.1 IMSI detach initiation by the mobile station . 105
4.3.4.2 IMSI detach procedure in the network . 106
4.3.4.3 IMSI detach completion by the mobile station. 106
4.3.4.4 Abnormal cases . 106
4.3.5 Abort procedure . 106
4.3.5.1 Abort procedure initiation by the network . 106
4.3.5.2 Abort procedure in the mobile station . 107
4.3.6 MM information procedure. 107
4.3.6.1 MM information procedure initiation by the network . 107
4.3.6.2 MM information procedure in the mobile station . 107
4.4 MM specific procedures . 107
4.4.1 Location updating procedure . 108
4.4.2 Periodic updating . 109
4.4.3 IMSI attach procedure . 110
4.4.4 Generic Location Updating procedure . 111
4.4.4.1 Location updating initiation by the mobile station . 111
4.4.4.1a Network Request for Additional mobile station Capability Information . 111
4.4.4.2 Identification request from the network . 111
4.4.4.3 Authentication by the network . 111
4.4.4.4 Security mode setting by the network . 112
4.4.4.5 Location Update Attempt Counter . 112
4.4.4.6 Location updating accepted by the network . 112
4.4.4.7 Location updating not accepted by the network . 114
4.4.4.8 Release of RR connection after location updating . 116
4.4.4.9 Abnormal cases on the mobile station side . 116
4.4.4.10 Abnormal cases on the network side . 118
4.4.5 Void . 119
4.4.6 Void . 119
4.4.7 eCall inactivity procedure . 119
4.5 Connection management sublayer service provision . 120
4.5.1 MM connection establishment . 120
4.5.1.1 MM connection establishment initiated by the mobile station . 120
4.5.1.2 Abnormal cases . 124
4.5.1.3 MM connection establishment initiated by the network . 125
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4.5.1.3.1 Mobile Terminating CM Activity . 125
4.5.1.3.2 Mobile Originating CM Activity $(CCBS)$ . 126
4.5.1.3.3 Paging response in Iu mode (Iu mode only) . 127
4.5.1.3.4 Paging response for CS fallback . 127
4.5.1.4 Abnormal cases . 128
4.5.1.5 MM connection establishment for emergency calls . 128
4.5.1.5a MM connection establishment for emergency calls for CS fallback . 129
4.5.1.6 Call re-establishment . 129
4.5.1.6.1 Call re-establishment, initiation by the mobile station . 129
4.5.1.6.2 Abnormal cases . 131
4.5.1.7 Forced release during MO MM connection establishment . 132
4.5.1.8 MM connection establishment due to SRVCC or vSRVCC handover . 132
4.5.1.9 MM connection establishment due to Dual Radio Voice Call Continuity (DRVCC) access
transfer . 133
4.5.2 MM connection information transfer phase . 133
4.5.2.1 Sending CM messages . 133
4.5.2.2 Receiving CM messages . 133
4.5.2.3 Abnormal cases . 133
4.5.3 MM connection release . 134
4.5.3.1 Release of associated RR connection . 134
4.5.3.2 Uplink release in a voice group call . 134
4.6 Receiving a MM STATUS message by a MM entity. . 134
4.7 Elementary mobility management procedures for GPRS services . 134
4.7.1 General . 134
4.7.1.1 Lower layer failure . 135
4.7.1.2 Ciphering of messages (A/Gb mode only) . 135
4.7.1.2a Integrity protection of layer 3 signalling messages (A/Gb mode only and when integrity
protection is required) . 135
4.7.1.2a.1 General . 135
4.7.1.2a.2 Integrity checking of GMM signalling messages in the MS . 135
4.7.1.2a.3 Integrity checking of layer 3 signalling messages in the network . 136
4.7.1.2a.4 Establishment of integrity protection of layer 3 signalling messages . 137
4.7.1.2a.5 Optional establishment of integrity protection in the user plane . 137
4.7.1.2a.6 Change of security keys . 137
4.7.1.3 P-TMSI signature . 138
4.7.1.4 Radio resource sublayer address handling . 138
4.7.1.4.1 Radio resource sublayer address handling (A/Gb mode only) . 138
4.7.1.5 P-TMSI handling . 140
4.7.1.5.1 P-TMSI handling in A/Gb mode . 140
4.7.1.5.2 P-TMSI handling in Iu mode . 140
4.7.1.5.3 Void . 140
4.7.1.5.4 Void . 140
4.7.1.6 Change of network mode of operation . 140
4.7.1.6.1 Change of network mode of operation in A/Gb mode (A/Gb mode only) . 140
4.7.1.6.2 Change of network mode of operation in Iu mode (Iu mode only) . 141
4.7.1.6.3 Change of network mode of operation at Iu mode to A/Gb mode inter-system change . 141
4.7.1.6.4 Change of network mode of operation at A/Gb mode to Iu mode inter-system change . 142
4.7.1.7 Intersystem change between A/Gb mode and Iu mode . 143
4.7.1.7a Intersystem change from S1 mode to A/Gb mode or S1 mode to Iu mode with ISR activated . 144
4.7.1.7b Intersystem change from S1 mode to A/Gb mode or S1 mode to Iu mode for eCall only MS

capable of eCall over IMS . 144
4.7.1.7c Return to packet idle mode for eCall only MS capable of eCall over IMS . 145
4.7.1.8 List of forbidden PLMNs for GPRS service . 145
4.7.1.8a Establishment of the PS signalling connection (Iu mode only) . 145
4.7.1.9 Release of the PS signalling connection (Iu mode only) . 146
4.7.1.10 Handling of 3GPP PS data off. 147
4.7.2 GPRS Mobility management timers and UMTS PS signalling connection control . 147
4.7.2.1 READY timer behaviour . 147
4.7.2.1.1 READY timer behaviour (A/Gb mode only) . 147
4.7.2.1.2 Handling of READY timer in the MS in Iu mode and S1 mode . 149
4.7.2.1.2a Handling of READY timer in the network in Iu mode and S1 mode . 149
4.7.2.2 Periodic routing area updating . 149
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4.7.2.3 PMM-IDLE mode and PMM-CONNECTED mode (Iu mode only) . 151
4.7.2.4 Handling of Force to standby in Iu mode (Iu mode only). 152
4.7.2.5 RA Update procedure for Signalling Connection Re-establishment (Iu mode only) . 152
4.7.2.6 Cell Update triggered by low layers . 152
4.7.2.7 Handling of timer T3302 . 152
4.7.2.8 Handling of timer T3324 (A/Gb mode, Iu mode and S1 mode) . 152
4.7.2.9 Power saving mode . 153
4.7.2.10 Extended idle-mode DRX cycle . 154
4.7.2.11 Interaction between power saving mode and extended idle mode DRX cycle . 155
4.7.2.12 Extended coverage for GSM . 155
4.7.3 GPRS attach procedure . 155
4.7.3.1 GPRS attach procedure for GPRS services . 157
4.7.3.1.1 GPRS attach procedure initiation . 157
4.7.3.1.2 GMM common procedure initiation . 159
4.7.3.1.3 GPRS attach accepted by the network . 159
4.7.3.1.4 GPRS attach not accepted by the network . 163
4.7.3.1.4a GPRS attach for emergency bearer services not accepted by the network (UTRAN Iu mode
only) . 167
4.7.3.1.4b Attach for initiating a PDN connection for emergency bearer services not accepted by the
network (UTRAN Iu mode only) . 168
4.7.3.1.5 Abnormal cases in the MS . 169
4.7.3.1.6 Abnormal cases on the network side . 171
4.7.3.2 Combined GPRS attach procedure for GPRS and non-GPRS services . 173
4.7.3.2.1 Combined GPRS attach procedure initiation . 173
4.7.3.2.2 GMM Common procedure initiation . 174
4.7.3.2.3 Combined GPRS attach accepted by the network . 174
4.7.3.2.4 Combined GPRS attach not accepted by the network . 176
4.7.3.2.5 Abnormal cases in the MS . 180
4.7.3.2.6 Abnormal cases on the network side . 180
4.7.4 GPRS detach procedure . 181
4.7.4.0 General . 181
4.7.4.1 MS initiated GPRS detach procedure . 181
4.7.4.1.1 MS initiated GPRS detach procedure initiation . 181
4.7.4.1.2 MS initiated GPRS detach procedure completion for GPRS services only . 182
4.7.4.1.3 MS initiated combined GPRS detach procedure com
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