5G NR Voice Solutions Overview and Deployment Guidelines.
In this paper: several aspects of the two main 5G voice solutions: VoNR and EPSFB. The performance study in this paper consists of call setup latency, breakdown of the delays, some aspects of in-call performance, and offers a comprehensive guide to network deployment towards a successful migration of VoLTE to EPSFB and VoNR.
[Source: MediaTek]
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dear experts. In LTE CSFB, voice centric UE will attach to EPC for PS domain & legacy 3G MSC for CS domain. In 5G supporting EPSFB, does UE attach to 5GC for PS domain & 4G EPC for IMS domain?
CSFB & EPSFB mechaism are almost the same. But they are different in deployment.
CSFB is deployed at the initial phase of LTE network because IMS is not supported, must use voice service in 3G.
But in 5G, IMS is already in use for VOLTE, 5GC may be already connected to IMS, 5G network also support VoNR. But due to 5G sites are few, voice users often move alot, to avoid frequently handover from 5G to 4G, 5G may apply EPSFB at 5G voice setup, UE will directly move to 4G for VoPS.
In my understanding of 5G Voice, UE just registers over IMS during Reg.
5GC & EPC take care of EPFSB via N26.
That’s why in Reg accept, UE doesn’t get differentiation of IMSFB or IMSo5G, unlike combined attach in LTE.
It just gets IMS over 3gpp and/or n3gpp.
If 5GC support VoNR, it will send VoNR capability parameter to UE in registration accept?
No, just whether IMS supported on 3gpp/n3gpp or not.
5GC support VoNR means 5GC is connected to IMS?
Yes 5GC can be directly connected to IMS or maybe via EPC through N26.
No way for UE to know.
I mean if 5GC is connected to IMS, supporting VoNR.
Will it send UE network VoNR capability parameters in registration accept?
It will still send only IMS over 3gpp supported, that’s it.
It can be EPSFB or VoNR.
No specific IE for VoNR.