LTE VoLTE and IMS Procedures

What This Covers

This category covers LTE voice and IMS-oriented procedures built on top of registration, bearer setup, and security.

Common nodes are the UE, eNB, MME, SGW, PGW, IMS entities, and policy-facing functions.

These procedures matter because voice service depends on both LTE EPC and IMS-side progression.

IMS Access and Registration

Procedures that establish IMS access and registration over LTE.

• LTE VoLTE Registration Procedure — IMS registration path over LTE.
• LTE SIP Session Establishment over IMS — Builds SIP session context over IMS.

Voice Call Setup

Procedures that set up LTE voice calls over IMS.

• LTE VoLTE Mobile Originated Call Procedure — Voice call setup from the UE side.
• LTE VoLTE Mobile Terminated Call Procedure — Voice call setup from the network side.

In-Call Service Handling

Procedures that handle bearer changes and call actions during an active session.

• LTE Dedicated Bearer Setup for VoLTE — Voice-oriented dedicated bearer setup.
• LTE VoLTE Call Hold / Resume — Mid-call hold and resume behavior.

Call Completion and Continuity

Procedures that release voice sessions or preserve continuity toward legacy access.

• LTE VoLTE Call Release Procedure — Voice call release and session closure.
• LTE SRVCC Procedure — Voice continuity toward legacy access.

Emergency and Messaging Services

Procedures that handle emergency calling and IMS-based messaging over LTE.

• LTE VoLTE Emergency Call Procedure — Emergency voice service over LTE and IMS.
• LTE SMS over IMS in LTE — SMS delivery over IMS in LTE service.

Related References

Related Sub-Procedures

• LTE Security Architecture — Read security context behind IMS-capable LTE service.
• LTE Bearer and Session Procedures — Open the bearer flows behind voice service.

Related Message Reference Pages

• PDN Connectivity Request — Open the message behind IMS APN service setup.
• Activate Dedicated EPS Bearer Context Request — Voice-related dedicated bearer setup reference.

Related Troubleshooting Pages

• LTE Security Architecture — Check security context issues behind voice-service failures.
• 3GPP Decoder — Inspect LTE and IMS fields during trace work.

Related LTE Categories

• Access and Registration Procedures
• Bearer and Session Procedures
• CSFB and Legacy Interworking Procedures

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