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Call Flow Procedures

Call flow pages explain how signaling messages move between the UE, radio network, and core network during real procedures such as registration, bearer or session setup, paging, mobility, recovery, and voice service handling.

LTE Call Flows

Reference pages for attach, service request, TAU, bearer setup, RRC procedures, paging, handover, VoLTE, interworking, and recovery.

LTE | EPC | NAS | RRC | S1AP

5G Call Flows

Reference pages for registration, PDU session establishment, mobility, RRC procedures, security, slicing, QoS, roaming, voice-related procedures, and user-plane path management.

5G NR | 5GC | NAS | RRC | NGAP

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New to telecom call flows?

Start with the most common end-to-end procedures:

Troubleshooting a signaling issue?

Open the procedure families most often involved in live failures:

Comparing LTE and 5G?

Use the LTE and 5G hubs side by side to compare:

Browse by Procedure

LTE

Access and Registration Procedures

RRC Connection and Security Procedures

Bearer and Session Procedures

Paging, Idle and Recovery Procedures

Mobility and Handover Procedures

Measurement and Optimization Procedures

VoLTE and IMS Procedures

CSFB and Legacy Interworking Procedures

Failure Reporting and Troubleshooting Procedures

LTE Advanced, Dual Connectivity and WLAN Procedures

Broadcast, MBMS and Group Delivery Procedures

NB-IoT, Sidelink and Special LTE Procedures

5G

Access and Registration

PDU Session Management

Mobility Procedures

RRC Procedures

Security Procedures

Voice Call Procedures

Network Slice Procedures

QoS Policy Procedures

Data Path Management

Roaming Procedures

NTN Procedures

Multi-Access Procedures