VoLTE (Voice over LTE) is a technology that carries voice calls over the 4G LTE data network. Compared to traditional 3G circuit-switched calls, it offers three key benefits: HD Voice for higher audio quality, faster call setup (from about 2 seconds down to about 1 second), and the ability to use data while on a call.
Before VoLTE, a method called CSFB (Circuit Switched Fallback) was used, which dropped the connection to 3G for voice calls. This approach took several seconds to connect and limited data to 3G speeds during calls. VoLTE eliminated these issues by keeping calls on 4G. NTT Docomo launched the first VoLTE service in Japan in 2014.
The transition to VoNR (Voice over New Radio), the voice call technology for 5G networks, is now underway. VoNR offers even lower latency than VoLTE and allows simultaneous use of 5G ultra-high-speed data and voice calls. The difference from VoIP and Wi-Fi Calling is that VoLTE runs natively on the carrier's mobile network.
The spread of VoLTE is closely tied to 3G network shutdowns (3G sunset). KDDI ended 3G service in March 2022, SoftBank in April 2024, and NTT Docomo is scheduled to end it in March 2026. After 3G shutdown, devices that do not support VoLTE will be unable to make voice calls, so users with older handsets need to upgrade to VoLTE-compatible devices. See VoIP Basics for an overview of voice call technologies.