What is the difference between VoNR in 5G and VoLTE in 4G?

  • My friend: Hi Ibrahim, I have a question for you.

    • Me: Please, go ahead.
  • My friend: I was wondering if VoNR and VoLTE are the same or different?

    • Me: Actually, they are similar in some aspects and different in other aspects. So, let me start with the similarities as both VoNR (Voice over New Radio) and VoLTE (Voice over LTE) are providing the voice service over 5G and 4G respectively using IMS (IP Multimedia Subsystem) network. I mean here by 5G, the 5G SA solution using option 2, not the 5G NSA solution. As if we are using 5G NSA, then VoLTE will still be used to introduce the voice services for the subscribers.
  • My friend: So, that means every 5G SA network will provide voice service to its users using VoNR, right?

    • Me: Not necessarily, as initially the 5G SA networks started without using VoNR service, due to the coverage limitations of 5G SA early deployments and were providing voice service using EPS fallback which is a method to switch users to the 4G during the voice call setup and here the user is using completely the 4G for both voice and data services as well. However, VoNR is the desired voice solution for 5G networks and the target that all 5G SA networks will use for voice services.
  • My friend: But how VoNR and VoLTE are different?

    • Me: Actually, VoNR should provide better performance than VoLTE such as lower call setup time due to lower latency in 5G compared with 4G. Also, VoNR will offer better voice quality than VoLTE due to use of EVS and H.265 codecs which are mandatory codecs for voice in 5G compared with VoLTE AMR and H.264. And don’t forget that using VoNR in 5G means that users will still enjoy the high data speed while making voice calls over 5G and not switched to the 4G network. Also, VoLTE is supporting CSFB and SRVCC handover to both 2G and 3G networks. While VoNR doesn’t support CSFB to 2G and 3G and only supports handover to 4G in Rel.15 and later in Rel.16, eSRVCC (enhanced Single Radio Voice Call Continuity) Handover was introduced towards 3G networks.
  • My friend: Thank you so much. You made it very clear.

    • Me: You are most welcome.

Linkedin: Ibrahim Sayed, PMP on LinkedIn: #5g #5gnr #5gtechnology | 22 comments

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