What are the available Voice Services in 5G?

5G NR
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  • In essence, 5G Standalone (SA) supports EPS Fallback and VoNR, while 5G Non-Standalone (NSA) supports VoLTE and CSFB.

    • In 5G, the availability of specific solutions for the voice service depends upon the Base Station architecture.
    • The solutions associated with each architecture are summarized in the figure below.
    • All architectures support OTT applications because these only require a data connection, which can be either an EPS Bearer towards the 4G core network or a PDU Session towards the 5G core network.
    • For 3/3a/3x, it’s 4G Master Node connected to 4G core for legacy voice. CS Fallback and VoLTE work, but CS Fallback may have slight delays due to extra signaling for 5G Secondary Node.
    • For 2 and 4/4a, it’s 5G Master Node connected to 5G core, requiring new 5G voice solutions like VoNR. No CS Fallback: alternatives are EPS Fallback (4G) and RAT Fallback (5G).
    • EPS Fallback redirects UE to LTE Base Station on 4G core, while RAT Fallback redirects UE to 5G Base Station on 5G core.

  • Notes:

    • CS Fallback is not supported when using the 5G core network.
    • The release 15 version of the 3GPP specifications does not support SRVCC for 5G. Speech service continuity at locations with noncontiguous 5G coverage relies upon Packet Switched inter-system handover towards 4G. SRVCC can then be completed from 4G if necessary.
    • SRVCC from 5G to 3G (UTRAN) is planned for the release 16 version of the 3GPP specifications.

  • Data Source:

    • 5G NR in Bullets

What are the available Voice Services in 5G
What are the available Voice Services in 5G1250Ă—551 132 KB

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NSA:In the NSA (Non-Standalone) architecture, voice services are directly built on the LTE network using the VoLTE (Voice over LTE) solution, as shown in Figure 1

SA:In the early stages of SA (Standalone) deployment, due to insufficient coverage and an immature end-to-end industry, when VoNR (Voice over NR) is not yet deployed (i.e., NR cannot provide voice service), voice services will fall back to the LTE side for communication, as shown in Figure 4 (EPS FB).

VoNR (Voice over NR) allows users to make voice calls directly over the NR network without falling back to LTE, offering a higher quality voice experience and faster data rates. VoNR is the final voice solution in the SA Option 2 architecture, as shown in Figure 3.

5G Voice Solutions

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