VoLTE Vs Vo5G | Difference between VoLTE and VoNR

This page compares VoLTE (Voice Over LTE) vs Vo5G (Voice Over 5G NR (New Radio)) and mentions difference between VoLTE and VoNR (Voice Over New Radio).

Introduction: Voice is used as fundamental service in cellular mobile communication systems. 1G was analog communication network which offered circuit switched voice services. CS (Circuit Switched) based voice and PS (Packet Switched) based data services are used in 2G/3G networks. 4G offered IP based services for both voice and data. IMS is a standard which defines telephony services, voice, messaging and video over IP network. Both 4G LTE and 5G NR (New Radio) offer IMS based voice over IP.

VoLTE delivers HD voice, faster call setup times and improved battery life. VoNR (Voice over 5G New Radio) delivers high speed, high bandwidth IP network connectivity and multi-service applications. VoNR is equivalent to VoLTE.

Voice Over 5G NR,Voice over NR,VoNR,Vo5G

Voice calls in LTE network are serviced using various options which include CSFB (Circuit Switched Fall back), VoIP (Voice over IP), In CSFB option, voice is offloaded to 2G/3G network from main 4G LTE network. In VoIP, handsets and 4G network should be VoIP compliant otherwise OTT (over-the-top) apps are used. The final option for voice over LTE is VoLTE which used IMS entity and voice is carried as VoIP packets. SIP (Session Initiation Protocol) is the key protocol for IMS architecture. IMS services include basic and advance services viz. voice/video call, IM messaging, SMS/MMS, voice mail, self care, video conference, cloud address book, social network integration, breakout to PSTN etc.

Voice services in 5G NR network are served by adopting various options such as EPS Fall Back, Voice over eNB with 5G core (VoeLTE) and Voice over NR (VoNR).

Difference between VoLTE and Vo5G

Following table mentions comparison between VoLTE and Vo5G with respect to various system parameters.

Parameters VoLTE VoNR
Frequency of operation As defined by LTE radio As defined by 5G new radio in SA (Standalone) scenario, as per LTE radio in NSA (Non Standalone) scenario
Core EPC (Evolved Packet Core) 5GC (5G core)
Call setup time Fast Faster than VoLTE due to low latency
Voice quality HD voice Better than VoLTE due to use of EVS and H.265 codecs
CSFB support It supports CSFB (Circuit Switched Fall Back) to 2G/3G. It does not support circuit switched voice calls.
Seamless handover to 3G Supported Supported using ICS (IMS centralized Service)

Refer advantages and disadvantages of Voice over LTE and Voice over 5G NR to understand difference between VoLTE and VoNR.

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