5G Voice Call Procedures
5G VoNR call flows show how IMS voice works over 5G standalone service, from IMS registration and voice PDU session setup through call setup, call modification, emergency handling, fallback, and continuity. Use this hub to jump into VoNR registration, IMS registration refresh, IMS PDU sessions, mobile originated and terminated calls, call release, hold and resume, emergency voice, EPS fallback, and SRVCC comparison flows.
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What This Covers
VoNR procedures use IMS registration and voice-capable PDU sessions to support native 5G voice service.
Call handling flows cover mobile originated calls, mobile terminated calls, call release, hold/resume, emergency voice, EPS fallback, and continuity comparison.
Use the links below to jump directly into IMS voice setup, VoNR calls, emergency voice, fallback, and SRVCC-related call flows.
VoNR Registration and Core Voice Entry
Procedures that prepare the UE for native voice service on 5G standalone.
- VoNR Registration — IMS registration over NR
- IMS Registration Refresh / Re-registration — Maintain IMS registration continuity over time
- IMS PDU Session Establishment for Voice — Voice-specific IMS data session setup
VoNR Call Handling
End-to-end procedures for outgoing calls, incoming calls, call modification, and release.
- VoNR Mobile Originated Call — UE initiates call
- VoNR Mobile Terminated Call — UE receives call
- VoNR Call Termination — End voice session
- VoNR Call Hold / Resume — Voice session modification
Emergency and Fallback Voice Paths
Voice procedures used when emergency service or fallback continuity changes the normal VoNR path.
- VoNR Emergency Call — Emergency voice service
- EPS Fallback — 5G to LTE voice fallback
- VoLTE Fallback / Voice Continuity Comparison — Compare fallback and continuity branches for voice
- SRVCC Procedure — Single Radio Voice Call Continuity to legacy CS voice