LTE Call Flow Procedures

Access and Registration Procedures

These procedures are used when the UE first enters LTE service and starts EPS registration.

• LTE Attach Procedure
• LTE Combined EPS / IMSI Attach Procedure
• LTE Emergency Attach Procedure
• LTE Service Request Procedure
• LTE Extended Service Request Procedure
• LTE Tracking Area Update Procedure
• LTE Periodic Tracking Area Update
• LTE Detach Procedure
• LTE Paging Procedure

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RRC Connection and Security Procedures

Procedures that establish or manage the dedicated LTE radio-control connection.

• LTE RRC Connection Setup Procedure
• LTE RRC Connection Reject Procedure
• LTE RRC Resume Procedure
• LTE Authentication Procedure
• LTE NAS Security Procedure
• LTE Security Mode Procedure
• LTE Initial Context Setup Procedure
• LTE UE Capability Transfer Procedure
• LTE DL / UL Information Transfer Procedure
• LTE RRC Re-establishment Procedure
• LTE RRC Connection Release Procedure

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Bearer and Session Procedures

Procedures that create the first usable PDN and bearer path in EPS.

• LTE Default EPS Bearer Establishment
• LTE APN / PDN Connectivity Setup Flow
• LTE Dedicated EPS Bearer Establishment
• LTE Dedicated Bearer Setup for VoLTE
• LTE Bearer Modification Procedure
• LTE E-RAB Modify Procedure
• LTE Bearer Release Procedure
• LTE E-RAB Release Procedure
• LTE E-RAB Setup Procedure

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Paging, Idle, and Recovery Procedures

Procedures that wake the UE from idle and restore active signaling.

• LTE Paging Procedure
• LTE Connection Release to Idle
• LTE Radio Link Failure and Recovery
• LTE RRC Re-establishment Procedure
• LTE RRC Connection Release Procedure
• LTE Cell Reselection Procedure
• LTE NAS Recovery After Radio Failure
• LTE Handover Failure and Recovery

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Mobility and Handover Procedures

Procedures that move the UE between LTE cells while staying inside LTE service.

• LTE Intra-LTE Handover Procedure
• LTE Intra-Frequency Handover
• LTE Inter-Frequency Handover
• LTE X2 Handover Procedure
• LTE S1 Handover Procedure
• LTE Inter-RAT Handover Procedure
• LTE Mobility From E-UTRA Procedure
• LTE Handover to UTRAN
• LTE Handover to GERAN
• LTE Handover to CDMA2000
• LTE Measurement-Controlled Handover
• LTE Handover Failure and Recovery
• LTE Conditional Handover / Conditional Reconfiguration

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Measurement and Optimization Procedures

Procedures that configure LTE measurement behavior and reporting rules.

• LTE Measurement Events Overview
• LTE Measurement Configuration Procedure
• LTE Measurement Reporting Procedure
• LTE Event A1 Measurement Procedure
• LTE Event A2 Measurement Procedure
• LTE Event A3 Measurement Procedure
• LTE Event A4 Measurement Procedure
• LTE Event A5 Measurement Procedure
• LTE Event A6 Measurement Procedure
• LTE Event B1 / B2 Inter-RAT Measurement Procedure
• LTE Inter-Frequency RSTD Measurement Indication
• LTE GNSS Measurement Reporting
• LTE ANR-Related Neighbor Measurement Flow
• LTE Application Layer Measurement Reporting

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VoLTE and IMS Procedures

These procedures establish the UE presence in IMS and must complete before normal VoLTE calling can begin.

• LTE VoLTE Registration Procedure
• LTE SIP Session Establishment over IMS
• LTE VoLTE Mobile Originated Call Procedure
• LTE VoLTE Mobile Terminated Call Procedure
• LTE Dedicated Bearer Setup for VoLTE
• LTE VoLTE Call Hold / Resume
• LTE VoLTE Call Release Procedure
• LTE SRVCC Procedure
• LTE VoLTE Emergency Call Procedure
• LTE SMS over IMS in LTE

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CSFB and Legacy Interworking Procedures

Procedures that move service from LTE into legacy voice handling.

• LTE CSFB Procedure
• LTE CSFB to 3G
• LTE CSFB to 2G
• LTE 1xCSFB / CDMA2000 Fallback Procedure
• LTE Handover From E-UTRA Preparation Request
• LTE UL Handover Preparation Transfer
• LTE PS Handover / SRVCC Preparation Flows

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Failure Reporting and Troubleshooting Procedures

Procedures that explain how LTE handles generic protocol and content errors.

• LTE Generic Error Handling Procedure
• LTE ASN.1 / Encoding Error Handling
• LTE Mandatory Field Missing Handling
• LTE Unknown / Not-Comprehended IE Handling
• LTE Failure Information Procedure
• LTE SCG Failure Information Procedure
• LTE NR SCG Failure Information
• LTE MCG Failure Information
• LTE Failure Type Determination

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LTE-Advanced, Dual Connectivity, and WLAN Procedures

Procedures that establish or change dual-connectivity behavior.

• LTE Dual Connectivity Procedure
• LTE SCG Configuration / Reconfiguration
• LTE Split Bearer Procedures
• LTE SCG Failure Recovery
• LTE NE-DC Release Procedure
• LTE WLAN Interworking Procedure
• LTE WLAN Status Reporting Procedure
• LTE WLAN Traffic Steering Procedure
• LTE LWA Procedure
• LTE LWIP Procedure

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Broadcast, MBMS, and Group Delivery Procedures

Procedures that handle LTE system information acquisition and broadcast behavior.

• LTE System Information Acquisition Procedure
• LTE MIB and SIB Acquisition Procedure
• LTE ETWS Notification Procedure
• LTE CMAS Notification Procedure
• LTE MBMS Counting Procedure
• LTE MBMS Interest Indication
• LTE MBMS PTM Bearer Procedure
• LTE SC-PTM Procedure

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NB-IoT, Sidelink, and Special LTE Procedures

Procedures that support NB-IoT access and system information handling.

• LTE NB-IoT Access Procedure
• LTE NB-IoT System Information Acquisition
• LTE NB-IoT Measurement Procedure
• LTE Sidelink Procedure
• LTE V2X Sidelink Procedure
• LTE Relay Node Reconfiguration
• LTE Sidelink Relay UE Procedure
• LTE Remote UE Relay Procedure
• LTE NTN-Oriented Special Cases

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Related References

• LTE Message Reference Pages — Browse NAS, LTE RRC, and S1AP message references.
• LTE Troubleshooting Pages — Open LTE troubleshooting paths by symptom or domain.
• LTE NAS Overview — Read LTE NAS mobility and session context.
• LTE RRC Overview — Read LTE radio-control procedures and states.
• LTE EPC / S1AP References — Open EPC-facing S1AP signaling references.
• IMS / VoLTE Reference Pages — Browse IMS and VoLTE reference material.

Related Technologies

• 5G NR Call Flow Procedures
• LTE Message Reference Pages
• IMS / VoLTE References
• Release / Standards Pages

Browse LTE Categories

• 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

Implementation Notes

Suggested breadcrumb: Home > Call Flows > LTE

Suggested internal links: /call-flows/lte/attach-procedure/ | /call-flows/lte/rrc-connection-setup/ | /call-flows/lte/volte-and-ims-procedures/ | /messages/lte/

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