Feature Description
Based on the presence or absence of the N26 interface, Evolved Packet System (EPS) Fallback opts to switch or redirect to EPS.
The AMF performs and involves in the following activities:
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It supports the IMS voice over PS (VoPS) session and indicates towards the UE during the Registration procedure.
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It sends the value of redirection-eps-fallback information elements towards the gNodeB.
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The redirection-eps-fallback IE is based on the UE 5GMM capability to support Request Type flag handover and CLI configuration for redirection-eps-fallback .
This feature supports the following functionalities:
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5GS interworking without N26 interface indicator in Registration Accept.
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Redirection for EPS fallback for voice as part of the ICSR
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Handover Request and Path Switch Request ACK to fill Redirection IE.
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N26, Xn, and N2 handovers