Service Request Procedure Call Flow
This section describes the Service Request Procedure call flow.

Step |
Description |
---|---|
1 |
The UE sends a Service Request with Service Type set to Emergency Services Fallback. |
2 |
The AMF sends the Initial UE Context Setup request or the Modify UE Context request. If the Emergency Fallback feature support CLI is configured at AMF, AMF sets the Emergency Fallback Indication IE toward gNB in either Initial Context Setup Request or UE Context Modification Request along with Service Accept towards UE. The NGAP IE of the target CN is set optionally as EPC or 5GC, if configured; else CN type is not included. If Emergency Fallback feature support CLI is not configured, AMF sends Service Reject with cause NO SUITABLE CELLS IN TRACKING AREA. |