Is SRVCC possible for 5G VoNR to 3G in case of poor coverage?

5G NR
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1

Hi Experts,
Is SRVCC possible for 5G VoNR to 3G in case of poor coverage?
Anyone working on VoNR?
Does we have separate IMS for 5G or shared with 4G IMS?

2

No, SRVCC and CSFB are not supported in 5G NR and is incompatible with legacy systems.

3

I’m seeing Rel16 mentioning SRVCC from 5G to 3G…
PSHO from 5G to 4G, no SRVCC to 4G.
Is this correct?

4

Yes you’re right,but the meaning is different.
In rel. 16, SRVCC will be supported implicitly by PSHO from NG-RAN to E-UTRAN.
The meaning is different because SRVCC from E-UTRAN to UTRAN was already supported in 4G LTE.
Hope it is clear now. :wink:

5

Thanks.
For data call transfer term PSHO used.
For voice call SRVCC.
It’s mentioned SRVCC from 5G to 3G.
PSHO from 5G to 4G.
N26 interface used for PSHO.

6

Hi ,

I think SRVCC from 5G to 3G mean to say is , 1st voice call HO between 5g to 4G and then SRVCC to 3G .Here Voice call HO possible between 5G(VONR) to LTE(VOLTE) using N26 interface between AMF and MME ( without N26 interface Voice call HO not possible between 5G to 4G N/W due to Voice interruption time) . For Voice call HO to complete ,max Voice Interruption time needed is ~300 m sec and using N26 interface it takes ~70 m sec (interruption time) . but without N26 interface Voice interruption time takes 700 m sec >300m sec(Max voice interruption time).