5G Call Flow Procedures
A structured reference for 5G end-to-end signaling procedures, including registration, service recovery, session control, mobility, RRC behavior, security, voice, roaming, ATSSS, and NTN flows.
Quick Links
Access & Registration
Covers initial access, registration, authentication entry points, service request triggers, and the end-to-end UE to AMF registration sequence in 5G networks.
PDU Session Management
Includes PDU session establishment, modification, release, SSC handling, and user-plane tunnel setup between the UE, AMF, SMF, and UPF.
- PDU Session Establishment
- PDU Session Modification
- PDU Session Release
- Network Requested PDU Session
- Secondary PDU Session Setup
- IMS PDU Session Establishment
- Emergency PDU Session Establishment
- SSC Mode Change / Session Continuity Handling
- Session Recovery after Mobility / Path Switch
- Session Reactivation after Idle/Inactive Return
Mobility Procedures
Focuses on handover, tracking area updates, inter-gNB mobility, path switch, and session continuity during movement across the network.
- Idle Mode Mobility
- Connected Mode Handover
- Inter-gNB Handover
- Inter-AMF Mobility
- Intra-gNB Handover
- Inter-RAT Handover
- LTE to 5G Inter-RAT Handover / Redirection
- EPS Fallback Procedure
- PSCell / Secondary Cell Change in EN-DC or MR-DC
- Dual Connectivity Mobility Reconfiguration
- RRC Inactive Resume with Mobility Context Change
RRC Procedures
Includes RRC setup, resume, reconfiguration, release, paging response, and other radio control exchanges between the UE and gNB.
Security Procedures
Describes authentication, NAS security activation, AS security setup, key derivation, and security mode related call flows in 5G.
Voice Call Procedures
Covers VoNR and IMS-related signaling such as registration support, session establishment, emergency handling, and fallback-related voice flows.
- VoNR Registration
- VoNR Mobile Originated Call
- VoNR Mobile Terminated Call
- VoNR Call Termination
- VoNR Call Hold / Resume
- VoNR Emergency Call
- IMS Registration Refresh / Re-registration
- IMS PDU Session Establishment for Voice
- EPS Fallback
- VoLTE Fallback / Voice Continuity Comparison
- VoLTE Call Flow and Procedures
- SRVCC Procedure
Network Slice Procedures
Captures slice selection, allowed NSSAI handling, rejected S-NSSAI scenarios, and slice-aware session establishment procedures.
QoS / Policy Procedures
Groups call flows related to QoS flow setup, policy control interaction, PCC updates, GBR handling, and session rule enforcement.
Data Path Management
Focuses on user-plane path creation, updates, and release between the access network and UPF for active data sessions.
Roaming Procedures
Explains home-routed and local breakout roaming call flows, inter-PLMN registration, security handling, and session continuity in roaming cases.
Non-Terrestrial Network (NTN) Procedures
Provides a place for satellite and other non-terrestrial 5G procedures where large delay, orbital mobility, and NTN-specific access handling must be managed.
Multi-Access Procedures
Covers traffic steering and multi-access continuity mechanisms such as ATSSS across 5G and Wi-Fi or other access networks.