Difference between VoLTE and VoNR (Vo5G)

Voice services have always been essential to mobile operators, and the need for voice calling is not likely to subside as people will always need to talk. So, even though we have many communication options at our disposal nowadays, including instant messaging etc., voice calling is still at the top of the list. Voice is one of those features that we often take for granted, but there is a considerable level of complexity involved in bringing voice services to us through cellular networks. This post aims to identify the main difference between two key voice capabilities VoLTE and VoNR.

VoLTE – Voice over LTE is a 4G technology

VoLTE or Voice over LTE (Long Term Evolution) is the voice calling capability in fourth-generation (4G) LTE networks. Before 4G LTE, the 2G and 3G mobile networks relied on the conventional circuit-switched technology to enable voice calls and text messages (SMS). The circuit-switched technology is not the most efficient as it establishes a dedicated connection between the mobile network and the phone for the entire call duration. The aim with 4G LTE was to transfer all cellular services, including voice and texts, to IP, which required the packet-switched capability. Even though both 2G and 3G networks had a packet-switched capability for data, the voice and text services were not delivered on packet-switched because it was impossible to ensure service quality. 4G networks do not have a circuit-switched part, and in line with the IP vision, they introduced Voice over LTE, an IP calling and messaging service based on packet-switched technology. LTE networks, however, have a 2G/3G circuit-switched backup option called the circuit-switched fallback (CSFB). At its simplest, CSFB allows a mobile phone to switch to the 2G or 3G circuit-switched connection for making and receiving phone calls. In VoLTE, an end-to-end quality of service (QoS) can be ensured for the call. The specifications are designed to ensure that the minimum bandwidth and codec requirements for voice calls align with the legacy circuit-switched networks. For VoLTE to function, the 4G mobile core network, Evolved Packet Core (EPC), works with IP Multimedia Subsystem (IMS) to enable rich communications, including voice and SMS. Have a look at our dedicated VoLTE post to learn how to locate VoLTE on your phone.

VoNR – Voice over NR is a 5G technology

VoNR stands for Voice over NR (New Radio) and is also referred to as Voice over 5G (Vo5G). It is the capability in the fifth generation (5G) of mobile networks that facilitates voice calls and text messages. Conceptually, VoNR and VoLTE do the same thing as they are both IP-based and rely on the packet-switched network. 5G NR networks are flexible in many ways, and their deployment models are also adaptable. 5G NR networks can co-exist with the 4G LTE, but they can also work as standalone mobile networks. In a standalone deployment scenario, 5G networks must be able to deliver all services, including voice which is where the VoNR capability comes in. Like VoLTE, VoNR also has an end-to-end QoS (Quality of Service) requirement to ensure service quality for voice calls and SMS. For VoNR to work, a mobile network requires a dedicated 5G core network that can work with IP Multimedia Subsystem (IMS) to enable rich communications, including voice calls and SMS. 5G networks have a dedicated 5G core network in a standalone deployment scenario, meaning that VoNR calls occur in a standalone scenario. In a non-stand-alone deployment scenario, 5G networks utilise the switching capabilities of the 4G core network, the EPC. When EPC is used, 5G networks make and receive calls through the VoLTE capability instead of VoNR.


VoLTE or Voice over LTE is an IP-based capability in 4G LTE networks to deliver high-quality voice calls and SMS through the data network instead of conventional circuit-switched lines. VoNR stands for Voice over New Radio (NR) and is an IP-based capability in 5G NR networks to deliver high-quality voice calls and SMS through the data network. VoNR is also referred to as Voice over 5G (Vo5G). VoLTE supports voice calls and messages in 4G LTE and non-stand-alone (NSA) 5G NR networks, whereas VoNR (Vo5G) supports voice calls and text messages in standalone (SA) 5G NR networks.

Here are some helpful downloads

Thank you for reading this post, I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need some extra support especially when preparing for a new job, or studying a new topic, or maybe just buying a new phone. Whatever you are trying to do, here are some downloads that can help you:

Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy which explains the network nodes e.g. BTS, MSC, GGSN etc.

Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience which is why I’ve carefully put together a few slides to get you started in no time. So if work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on product overview and product roadmap.

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