LTE CSFB Procedures | 2G, 3G, 1xCSFB & SRVCC
LTE CSFB and legacy interworking procedures show how LTE voice or mobility leaves pure EPS service and falls back to 3G, 2G, CDMA2000, or SRVCC continuity paths. Use this hub to jump into CSFB, CSFB to 3G, CSFB to 2G, 1xCSFB, handover preparation, and SRVCC preparation call flows.
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What This Covers
LTE CSFB procedures move voice service from LTE packet access toward legacy circuit-switched domains.
Legacy interworking flows prepare fallback or continuity toward 3G, 2G, CDMA2000, and SRVCC paths.
Use the links below to jump directly into CSFB, 3G fallback, 2G fallback, 1xCSFB, handover preparation, and SRVCC call flows.
CS Fallback Entry
Procedures that move service from LTE into legacy voice handling.
- LTE CSFB Procedure — Main LTE circuit-switched fallback path.
- LTE CSFB to 3G — Fallback path from LTE to UMTS.
- LTE CSFB to 2G — Fallback path from LTE to GSM.
- LTE 1xCSFB / CDMA2000 Fallback Procedure — Fallback path from LTE to CDMA2000 voice handling.
Interworking Signaling Support
Procedures that prepare or transfer signaling for legacy interworking.
- LTE Handover From E-UTRA Preparation Request — Preparation signaling for legacy interworking handover.
- LTE UL Handover Preparation Transfer — Uplink preparation transfer for interworking mobility.
Voice Continuity and Legacy Transition
Procedures that preserve or prepare voice continuity during legacy transition.
- LTE PS Handover / SRVCC Preparation Flows — Voice continuity and legacy preparation paths.