What is the difference between iRAT Handover and SRVCC for 4G & 5G?

SRVCC is handover to 3G.

For the handovers between 4G 5G and wifi, Voice call continues over IP session.

5G to 4G HO, you mean to iRAT HO, right?

Yup! :wink:

So from 5G perspective, we can say 3 solutions to legacy:

  • EPS fall back
  • IRAT Ho
  • eSRVCC
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eSRVCC is defined in R10, not between 5G and 4G.

5G started with R15.

  • SRVCC is for Voice call continuity.
  • eSRVCC is for PS session continuity (in addition to the Voice).
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But even in SRVCC the PS session was handover to SGSN if it falls back to 3G network in LTE.

That’s an intermediate solution in evolution to VoNR.

VoNR is much advanced compared to VoLTE for marked differences like new codecs (3gpp IVAS) resulting in higher capacities than 3gpp EVS.

In this post there are also some good answer by @MOHAMED_SALAMA :point_down: