ETSI TS 129 502 V19.6.0 (2026-03)

5G; 5G System; Session Management Services; Stage 3 (3GPP TS 29.502 version 19.6.0 Release 19)

RTS/TSGC-0429502vj60

General Information

• Status: Not Published
• Technical Committee: 3GPP CT 4 - MAP/CAMEL/GTP/BCH/SS/TrFO/IMS/GUP/WLAN (formely CN4)
• Current Stage: 8 - Draft receipt by ETSI Secretariat
• Completion Date: 10-Mar-2026

Standards Content (Sample)

TECHNICAL SPECIFICATION
5G;
5G System;
Session Management Services;
Stage 3
(3GPP TS 29.502 version 19.6.0 Release 19)


3GPP TS 29.502 version 19.6.0 Release 19 1 ETSI TS 129 502 V19.6.0 (2026-03)

Reference
RTS/TSGC-0429502vj60
Keywords
5G
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ETSI
3GPP TS 29.502 version 19.6.0 Release 19 2 ETSI TS 129 502 V19.6.0 (2026-03)
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ETSI
3GPP TS 29.502 version 19.6.0 Release 19 3 ETSI TS 129 502 V19.6.0 (2026-03)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 10
1 Scope . 12
2 References . 12
3 Definitions and abbreviations . 14
3.1 Definitions . 14
3.2 Abbreviations . 14
4 Overview . 15
4.1 Introduction . 15
5 Services offered by the SMF . 15
5.1 Introduction . 15
5.2 Nsmf_PDUSession Service . 16
5.2.1 Service Description . 16
5.2.2 Service Operations . 17
5.2.2.1 Introduction . 17
5.2.2.2 Create SM Context service operation . 18
5.2.2.2.1 General . 18
5.2.2.2.2 EPS to 5GS Idle mode mobility using N26 interface (with or without data forwarding) . 22
5.2.2.2.3 EPS to 5GS Handover Preparation using N26 interface . 24
5.2.2.2.4 I-SMF Insertion, Change or Removal during Xn based Handover . 25
5.2.2.2.5 I-SMF Insertion, Change or Removal during N2 based Handover . 26
5.2.2.2.6 Service Request with I-SMF insertion/change/removal or with V-SMF change . 26
5.2.2.2.7 Registration procedure for a UE with a PDU session with I-SMF or V-SMF insertion, change

and removal . 27
5.2.2.2.8 SMF Context Transfer procedure, LBO or no Roaming, no I-SMF . 28
5.2.2.2.9 I-SMF Context Transfer procedure . 28
5.2.2.2.10 Handover between 3GPP and non-3GPP accesses with I-SMF insertion/removal or V-SMF
change . 29
5.2.2.2.11 Void . 29
5.2.2.2.12 SMF triggered I-SMF selection/removal or V-SMF selection . 29
5.2.2.3 Update SM Context service operation. 30
5.2.2.3.1 General . 30
5.2.2.3.2 Activation and Deactivation of the User Plane connection of a PDU session . 33
5.2.2.3.2.1 General . 33
5.2.2.3.2.2 Activation of User Plane connectivity of a PDU session . 34
5.2.2.3.2.3 Deactivation of User Plane connectivity of a PDU session . 35
5.2.2.3.2.4 Changing the access type of a PDU session from non-3GPP access to 3GPP access during
a Service Request procedure . 36
5.2.2.3.3 Xn Handover . 37
5.2.2.3.4 N2 Handover . 38
5.2.2.3.4.1 General . 38
5.2.2.3.4.2 N2 Handover Preparation . 39
5.2.2.3.4.3 N2 Handover Execution . 41
5.2.2.3.4.4 N2 Handover Cancellation . 42
5.2.2.3.5 Handover between 3GPP and untrusted non-3GPP access procedures . 42
5.2.2.3.5.1 General . 42
5.2.2.3.5.2 Handover of a PDU session without AMF change or with target AMF in same PLMN . 42
5.2.2.3.6 Inter-AMF change or mobility . 43
5.2.2.3.7 RAN Initiated QoS Flow Mobility . 44
5.2.2.3.8 EPS to 5GS Handover using N26 interface . 45
5.2.2.3.8.1 General . 45
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3GPP TS 29.502 version 19.6.0 Release 19 4 ETSI TS 129 502 V19.6.0 (2026-03)
5.2.2.3.8.2 EPS to 5GS Handover Preparation . 45
5.2.2.3.8.3 EPS to 5GS Handover Execution . 45
5.2.2.3.8.4 EPS to 5GS Handover Cancellation . 46
5.2.2.3.8.5 EPS to 5GS Handover Failure . 46
5.2.2.3.9 5GS to EPS Handover using N26 interface . 46
5.2.2.3.9.1 General . 46
5.2.2.3.9.2 Data forwarding tunnels setup during 5GS to EPS handover . 46
5.2.2.3.9.3 Indirect data forwarding tunnels removal for 5GS to EPS handover cancellation or failure . 47
5.2.2.3.10 P-CSCF Restoration Procedure via AMF . 47
5.2.2.3.11 AMF requested PDU Session Release due to duplicated PDU Session Id . 48
5.2.2.3.12 AMF requested PDU Session Release due to slice not available . 48
5.2.2.3.13 Indirect Data Forwarding Tunnel establishment during N2 based Handover with I-SMF . 48
5.2.2.3.13A Indirect Data Forwarding Tunnel removal during N2 based Handover with I-SMF . 49
5.2.2.3.14 Request to forward buffered downlink data packets at I-UPF . 50
5.2.2.3.15 Connection Suspend procedure . 51
5.2.2.3.16 Connection Resume in CM-IDLE with Suspend procedure . 51
5.2.2.3.17 AMF requested PDU Session Release due to Network Slice-Specific Authentication and
Authorization failure or revocation . 52
5.2.2.3.18 5GS to EPS Idle mode mobility using N26 interface with data forwarding . 52
5.2.2.3.19 AMF requested PDU Session Release due to Control Plane Only indication associated with

PDU Session is not applicable any longer . 53
5.2.2.3.20 AMF requested PDU Session Release due to ODB changes . 53
5.2.2.3.21 N9 Forwarding Tunnel establishment between Branching Points or UL CLs controlled by
different I-SMFs . 53
5.2.2.3.22 Remote UE Report during 5G ProSe Communication via 5G ProSe Layer-3 UE-to-Network
Relay without N3IWF procedure. 54
5.2.2.3.23 AMF requested PDU Session Release due to V/I-SMF failure . 54
5.2.2.3.24 Connection Inactive procedure with CN based MT communication handling . 55
5.2.2.3.25 UE Triggered Connection Resume in RRC Inactive procedure . 55
5.2.2.3.26 AMF requested PDU Session Release due to Network Slice instance not available . 56
5.2.2.3.27 AMF requested PDU Session Release due to MBSR not authorized . 57
5.2.2.3.28 AMF correlated UDM Re-Discovery for UDR Restoration during Subscription Data

Migration . 57
5.2.2.3.29 AMF indication of AMF Data Restoration resynchronization is initiated . 57
5.2.2.4 Release SM Context service operation . 57
5.2.2.4.1 General . 57
5.2.2.5 Notify SM Context Status service operation . 60
5.2.2.5.1 General . 60
5.2.2.6 Retrieve SM Context service operation. 63
5.2.2.6.1 General . 63
5.2.2.7 Create service operation . 66
5.2.2.7.1 General . 66
5.2.2.7.2 EPS to 5GS Idle mode mobility . 71
5.2.2.7.3 EPS to 5GS Handover Preparation . 71
5.2.2.7.4 N2 Handover Preparation with I-SMF Insertion . 72
5.2.2.7.5 Xn Handover with I-SMF Insertion . 72
5.2.2.7.6 UE Triggered Service Request with I-SMF Insertion. 73
5.2.2.8 Update service operation . 73
5.2.2.8.1 General . 73
5.2.2.8.2 Update service operation towards H-SMF or SMF . 75
5.2.2.8.2.1 General . 75
5.2.2.8.2.2 UE or network (e.g. AMF, V-SMF, I-SMF) requested PDU session modification . 76
5.2.2.8.2.3 UE requested PDU session release . 77
5.2.2.8.2.4 EPS to 5GS Handover Execution . 77
5.2.2.8.2.5 Handover between 3GPP access and untrusted or trusted non-3GPP access . 78
5.2.2.8.2.6 P-CSCF Restoration Procedure via AMF . 79
5.2.2.8.2.7 Addition of PSA and BP or UL CL controlled by I-SMF . 79
5.2.2.8.2.8 Removal of PSA and BP or UL CL controlled by I-SMF. 79
5.2.2.8.2.9 Change of PSA for IPv6 multi-homing or UL CL controlled by I-SMF . 80
5.2.2.8.2.10 PDU Session modification with I-SMF or V-SMF change . 80
5.2.2.8.2.11 Sending by I-SMF of N4 notifications related with traffic usage reporting . 81
5.2.2.8.2.12 N2 Handover Execution with I-SMF Insertion . 81
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3GPP TS 29.502 version 19.6.0 Release 19 5 ETSI TS 129 502 V19.6.0 (2026-03)
5.2.2.8.2.13 N2 Handover Cancellation with I-SMF Insertion . 82
5.2.2.8.2.14 EPS to 5GS Handover Cancellation . 82
5.2.2.8.2.15 5G-AN requested PDU session resource release . 82
5.2.2.8.2.16 Xn Handover with or without I-SMF or V-SMF Change . 83
5.2.2.8.2.17 EPS to 5GS Handover Failure . 83
5.2.2.8.2.18 EPS Bearer ID revocation . 84
5.2.2.8.2.19 Network requested PDU session release . 84
5.2.2.8.2.20 N2 Handover Execution with or without I-SMF or V-SMF Change . 84
5.2.2.8.2.21 Reporting of satellite backhaul change to (H-)SMF . 84
5.2.2.8.2.22 Simultaneous change of PSA and BP or UL CL controlled by I-SMF . 85
5.2.2.8.2.23 Service Request without I-SMF/V-SMF Change or with I-SMF/V-SMF Change or with I-
SMF Insertion . 85
5.2.2.8.2.24 Remote UE Report during 5G ProSe Communication via 5G ProSe Layer-3 UE-to-
Network Relay without N3IWF . 87
5.2.2.8.2.25 AMF correlated UDM Re-Discovery for UDR Restoration during Subscription Data
Migration . 87
5.2.2.8.2.26 AMF indication of AMF Data Restoration resynchronization is initiated . 87
5.2.2.8.2.27 Update of PDU Session with Non-3GPP Device Connection Information . 87
5.2.2.8.2.28 Reporting of UpCnxState change to (H-)SMF . 87
5.2.2.8.3 Update service operation towards V-SMF or I-SMF . 88
5.2.2.8.3.1 General . 88
5.2.2.8.3.2 Network (e.g. H-SMF, SMF) requested PDU session modification . 89
5.2.2.8.3.3 Network (e.g. H-SMF, SMF) or UE requested PDU session release . 90
5.2.2.8.3.4 Handover between 3GPP and untrusted non-3GPP access, from 5GC-N3IWF to EPS or
from 5GS to EPC/ePDG . 91
5.2.2.8.3.5 EPS Bearer ID assignment . 91
5.2.2.8.3.6 Addition of PSA and BP or UL CL controlled by I-SMF . 92
5.2.2.8.3.7 Removal of PSA and BP or UL CL controlled by I-SMF. 92
5.2.2.8.3.8 Change of PSA for IPv6 multi-homing or UL CL controlled by I-SMF . 93
5.2.2.8.3.9 Policy update procedures with an I-SMF . 93
5.2.2.8.3.10 Simultaneous change of PSA and BP or UL CL controlled by I-SMF . 94
5.2.2.8.3.11 Network (e.g. AMF) triggered network slice replacement with PDU session retained . 94
5.2.2.8.3.12 NetLoc Information Retrieval over N16/N16a . 95
5.2.2.9 Release service operation . 95
5.2.2.9.1 General . 95
5.2.2.10 Notify Status service operation . 96
5.2.2.10.1 General . 96
5.2.2.11 Send MO Data service operation . 98
5.2.2.11.1 General . 98
5.2.2.12 Transfer MO Data service operation . 99
5.2.2.12.1 General . 99
5.2.2.13 Transfer MT Data service operation . 100
5.2.2.13.1 General . 100
5.2.2.14 Retrieve service operation . 101
5.2.2.14.1 General . 101
5.2.3 General procedures . 102
5.2.3.1 Transfer of NAS SM information between UE and H-SMF for Home Routed PDU sessions . 102
5.2.3.1.1 General . 102
5.2.3.1.2 V-SMF Behaviour . 102
5.2.3.1.3 H-SMF Behaviour . 102
5.2.3.2 Transfer of NAS SM information between UE and SMF for PDU sessions with an I-SMF . 103
5.2.3.2.1 General . 103
5.2.3.3 Detection and handling of late arriving requests . 103
5.2.3.3.1 Handling of requests which collide with an existing SM context or PDU session context . 103
5.2.3.3.1.1 General . 103
5.2.3.3.1.2 Principles . 103
5.2.3.3.2 Detection and handling of requests which have timed out at the HTTP client . 103
5.2.3.3.2.1 General . 103
5.2.3.4 UE Location Information . 104
6 API Definitions . 104
6.1 Nsmf_PDUSession Service API . 104
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3GPP TS 29.502 version 19.6.0 Release 19 6 ETSI TS 129 502 V19.6.0 (2026-03)
6.1.1 API URI . 104
6.1.2 Usage of HTTP . 105
6.1.2.1 General . 105
6.1.2.2 HTTP standard headers . 105
6.1.2.2.1 General . 105
6.1.2.2.2 Content type . 105
6.1.2.3 HTTP custom headers . 105
6.1.2.3.1 General . 105
6.1.2.3.2 3gpp-Sbi-Origination-Timestamp. 106
6.1.2.4 HTTP multipart messages . 106
6.1.2.5 HTTP/2 request retries . 106
6.1.3 Resources . 107
6.1.3.1 Overview . 107
6.1.3.2 Resource: SM contexts collection . 109
6.1.3.2.1 Description . 109
6.1.3.2.2 Resource Definition . 109
6.1.3.2.3 Resource Standard Methods . 110
6.1.3.2.3.1 POST. 110
6.1.3.2.4 Resource Custom Operations . 114
6.1.3.3 Resource: Individual SM context . 114
6.1.3.3.1 Description . 114
6.1.3.3.2 Resource Definition . 114
6.1.3.3.3 Resource Standard Methods . 114
6.1.3.3.4 Resource Custom Operations . 114
6.1.3.3.4.1 Overview . 114
6.1.3.3.4.2 Operation: modify . 115
6.1.3.3.4.2.1 Description . 115
6.1.3.3.4.2.2 Operation Definition . 115
6.1.3.3.4.3 Operation: release . 119
6.1.3.3.4.3.1 Description . 119
6.1.3.3.4.3.2 Operation Definition . 119
6.1.3.3.4.4 Operation: retrieve . 120
6.1.3.3.4.4.1 Description . 120
6.1.3.3.4.4.2 Operation Definition . 120
6.1.3.3.4.5 Operation: send-mo-data . 121
6.1.3.3.4.5.1 Description . 121
6.1.3.3.4.5.2 Operation Definition . 121
6.1.3.4 Void. 123
6.1.3.5 Resource: PDU sessions collection (H-SMF or SMF) . 123
6.1.3.5.1 Description . 123
6.1.3.5.2 Resource Definition . 123
6.1.3.5.3 Resource Standard Methods . 123
6.1.3.5.3.1 POST. 123
6.1.3.5.4 Resource Custom Operations . 126
6.1.3.5.4.1 Overview . 126
6.1.3.6 Resource: Individual PDU session (H-SMF or SMF) . 126
6.1.3.6.1 Description . 126
6.1.3.6.2 Resource Definition . 127
6.1.3.6.3 Resource Standard Methods . 127
6.1.3.6.4 Resource Custom Operations . 127
6.1.3.6.4.1 Overview . 127
6.1.3.6.4.2 Operation: modify . 127
6.1.3.6.4.2.1 Description . 127
6.1.3.6.4.2.2 Operation Definition . 127
6.1.3.6.4.3 Operation: release . 129
6.1.3.6.4.3.1 Description . 129
6.1.3.6.4.3.2 Operation Definition . 129
6.1.3.6.4.4 Operation: transfer-mo-data . 130
6.1.3.6.4.4.1 Description . 130
6.1.3.6.4.4.2 Operation Definition . 130
6.1.3.6.4.5 Operation: retrieve . 131
6.1.3.6.4.5.1 Description . 131
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6.1.3.6.4.5.2 Operation Definition . 131
6.1.3.7 Resource: Individual PDU session (V-SMF or I-SMF) . 132
6.1.3.7.1 Description . 132
6.1.3.7.2 Resource Definition . 132
6.1.3.7.3 Resource Standard Methods . 132
6.1.3.7.3.1 POST. 132
6.1.3.7.4 Resource Custom Operations . 134
6.1.3.7.4.1 Overview . 134
6.1.3.7.4.2 Operation: modify . 134
6.1.3.7.4.2.1 Description . 134
6.1.3.7.4.2.2 Operation Definition . 134
6.1.3.7.4.3 Operation: transfer-mt-data . 137
6.1.3.7.4.3.1 Description . 137
6.1.3.7.4.3.2 Operation Definition . 137
6.1.4 Custom Operations without associated resources . 138
6.1.5 Notifications . 138
6.1.5.1 General . 138
6.1.5.2 SM Context Status Notification . 139
6.1.5.2.1 Description . 139
6.1.5.2.2 Notification Definition . 139
6.1.6 Data Model . 140
6.1.6.1 General . 140
6.1.6.2 Structured data types . 147
6.1.6.2.1 Introduction . 147
6.1.6.2.2 Type: SmContextCreateData . 148
6.1.6.2.3 Type: SmContextCreatedData . 165
6.1.6.2.4 Type: SmContextUpdateData .
...