Voice over LTE (VoLTE)
Discover how VoLTE revolutionizes mobile voice communication, supports the transition from 2G and 3G networks to modern IP-based technologies, and unlocks advanced services for communication service providers (CSPs) and users alike. With VoLTE serving as a foundation for 5G Voice and beyond, it is a cornerstone of future mobile communication.
From circuits to packets: The VoLTE story
VoLTE, short for "Voice over LTE," is a technology that enables voice calls over LTE networks, commonly known as 4G networks. Unlike older technologies that require separate infrastructure for voice and data, VoLTE integrates voice communication directly into the 4G network, enabling both standard phone calls, advanced services beyond traditional voice communication, and emergency services like calling the police on the same efficient system.
By replacing the circuit-switched systems of 2G and 3G with an all-IP (Internet Protocol) approach, VoLTE delivers faster call setup times, enhanced call quality with EVS (Enhanced Voice Services), seamless WiFi calling, and the flexibility to switch seamlessly between voice and video calls. Future codecs like IVAS (Immersive Voice and Audio Services) further improve clarity and enable a new standard of high-definition communication. This makes it the gold standard for voice communication on modern mobile networks.
How does VoLTE work?
How VoLTE relates to VoIP
VoLTE and VoIP (Voice over Internet Protocol) share a foundation in IP-based technology but are designed for distinct environments. VoLTE is tailored for mobile networks, utilizing LTE (4G) infrastructure to deliver high-quality, reliable voice calls integrated with mobile features like emergency calls and seamless roaming. It prioritizes voice traffic on the network, ensuring consistent quality even during peak usage.
In contrast, VoIP operates over any internet-based network, such as Wi-Fi or broadband, and is commonly used in popular video conferencing and communication applications. While VoIP offers flexibility across various devices, its reliability and call quality depend on the stability of the internet connection. Unlike VoLTE, VoIP lacks the carrier-grade features and mobile integration that make VoLTE a seamless upgrade for traditional telephony. Additionally, VoIP requires communication applications to be installed on devices, whereas VoLTE is natively integrated into mobile devices like smartphones, ensuring a more seamless user experience despite VoIP's flexibility across various devices.
Feature | VoLTE | VoIP |
---|---|---|
Connectivity | Mobile devices with LTE/WiFi compatibility | Desktop/mobile devices, VoIP phones |
Network type | Requires 4G LTE network, and works seamlessly with 5G and WiFi | Works over broadband/Wi-Fi internet |
Integration | Built into the phone’s dialer | Requires a third-party app |
Reliability | More reliable (uses prioritized mobile networks) | Depends on Wi-Fi/data quality |
Emergency calls | Natively supported and prioritized by the mobile network | The ability to make emergency calls with VoIP depends on the service provider |
Call quality | Prioritizes voice data with advanced codecs like EVS, supports WiFi calling | Possible jitter/latency from internet connection |
Costs | Included in smartphone plans | Unlimited domestic calling included in monthly VoIP plans |
Key benefits for CSPs
While VoLTE brings noticeable improvements for end users, it was primarily implemented to address challenges faced by communication service providers. By transitioning to IP-based technology, CSPs have been able to optimize their networks and offer more advanced services. Key benefits include:
Efficient use of network resources
VoLTE replaces the less efficient circuit-switched technology used in 2G and 3G with a packet-based IP system. This transition allows CSPs to maximize the utilization of their network resources, enabling them to handle voice and data more effectively on the same infrastructure.
Expanded service capabilities
Built on the IMS framework, VoLTE enables CSPs to deliver innovative services such as WiFi calling, video calling (ViLTE), and seamless multi-device integration. These advanced offerings enhance the customer experience and open opportunities for CSPs to differentiate their services with value-added features.
Improved roaming experience
Unlike 3G roaming, which often limited the access to home-country features, VoLTE allows users to maintain their regular services – including call waiting, voicemail, and caller ID – while roaming internationally. This ensures a seamless experience for customers traveling abroad, enhancing their satisfaction and loyalty.
Enhanced call features
VoLTE also supports specialized capabilities like branded enterprise communication solutions and robust fraud detection mechanisms. These features empower CSPs to go beyond traditional voice services, offering secure and tailored communication solutions that meet the demands of businesses and consumers alike.
Technical and infrastructure requirements for VoLTE deployment
The deployment of VoLTE requires a modern and robust network infrastructure to deliver high-quality, reliable voice services. CSPs must ensure that their networks have the necessary components and configurations to support VoLTE effectively.
IMS: The Core of VoLTE
At the heart of VoLTE lies the IMS, a critical architectural component for enabling multimedia services like voice over IP networks. IMS handles session management, call control, and routing, making it indispensable for VoLTE deployment. The shift from circuit-switched to IP-based networks was driven by the efficiency of IP technology and its ability to support richer communication services. Without an IMS system, VoLTE cannot function.
Essential network features and optimization
VoLTE deployment also requires specific features in both the radio access network (RAN) and the packet core network to ensure compatibility with the IMS. Additionally, precise radio network tuning is essential to optimize call quality and minimize issues like dropped calls or poor audio performance. This tuning process aligns the network to the unique requirements of handling voice traffic over LTE, ensuring a seamless user experience.
Deployment models and considerations

VoLTE deployment requires careful planning and consideration of infrastructure, technology choices, and long-term scalability. Ericsson currently deploys VoLTE on its proprietary cloud platforms, including Ericsson Cloud Native Infrastructure (CNIS), while supporting third-party platforms like VMware and Red Hat OpenStack. This flexible approach allows CSPs to leverage existing infrastructure and expertise. Additionally, Ericsson is advancing deployment options by exploring as-a-service models, and flexible consumption.
CSPs must evaluate key factors when deploying VoLTE. A robust IMS and optimized radio and packet core networks are critical for supporting reliable voice traffic. Comprehensive 4G coverage and spectrum availability are essential for delivering quality services, while VoLTE-compatible devices and roaming agreements play vital roles in adoption and seamless international connectivity. Future-proofing deployments is also crucial, ensuring compatibility with 5G core networks and emerging technologies. As CSPs transition to 5G voice, leveraging advanced IMS features and tuning networks for new capabilities will be essential for maintaining high-quality service and a smooth evolution.
Advanced services enabled by VoLTE and IMS
The Ericsson VoLTE offering
Ericsson’s VoLTE capable solutions encompass all of the communication core and radio network components, and professional deployment and tuning services necessary to provide high-quality and innovative voice use cases. The solutions enable consumer voice services for smartphones, smart watches and smart speakers, but also build a foundation for high-quality mobile voice and communication services and collaboration services for businesses, enterprises and industries.
The IMS solutions can be delivered with short time-to-market as pre-integrated and verified solutions and can improve total cost of ownership and reduce network operation and maintenance costs.

Why choose Ericsson?
Explore our portfolio enabling VoLTE
The future of VoLTE
Looking ahead: VoLTE as the foundation for 5G voice
High-quality voice calls over 4G LTE networks, leveraging IP-based technology for improved efficiency, clarity, and reliability.
Seamless switch from 5G to VoLTE in areas with limited 5G coverage, ensuring uninterrupted voice services. Single Radio Voice Call Continuity (SRVCC) enables seamless handover from 4G to existing GSM and WCDMA networks when necessary.
Native 5G voice technology delivering enhanced call quality, consistent data speeds, and advanced features on fully deployed 5G networks.
The role of cloud-based VoLTE in the 5G voice evolution
Hardware independence
Cloud-based VoLTE eliminates the reliance on proprietary hardware by virtualizing network functions, enabling deployment on a wide range of commercial off-the-shelf (COTS) hardware. This independence allows CSPs to reduce costs associated with specialized equipment and simplifies the supply chain. Additionally, it provides the flexibility to deploy VoLTE on diverse cloud environments, aligning with each CSP’s strategic goals.
Automation
Automation is a core advantage of cloud-based VoLTE, leveraging centralized orchestration tools to streamline network operations. Tasks such as provisioning, scaling, and updating network resources can be automated, reducing the need for manual intervention and lowering operational complexity. This not only accelerates service deployment but also minimizes human error, ensuring a more reliable and efficient network.
Business agility
The agility provided by cloud-based VoLTE empowers CSPs to respond quickly to market demands and evolving customer needs. With the ability to scale network resources dynamically and introduce new services rapidly, CSPs can stay ahead of competitors while meeting the expectations of users. This flexibility is especially valuable in adapting to fluctuating traffic patterns and exploring new revenue streams through innovative services like tailored voice solutions or differentiated network slices.