VoLTE / VoNR / VoWiFi Compatibility Checker

VoLTE (Voice over LTE) is a technology that carries voice calls over the 4G LTE data network instead of falling back to 2G/3G. It provides HD voice quality (AMR-WB or EVS codecs), faster call setup (under 2 seconds vs 5-7s on CSFB), and allows simultaneous voice and data. VoLTE is defined in 3GPP TS 23.228 (IMS architecture) and requires both operator and device support.

VoNR (Voice over New Radio) is the 5G equivalent of VoLTE. It carries voice calls natively over the 5G NR network in Standalone (SA) mode without any LTE fallback. VoNR requires a 5G SA core network (5GC), IMS registration over NR, and device support. As of 2026, VoNR deployments are still limited, most 5G voice calls use EPS Fallback to VoLTE.

VoWiFi (Voice over Wi-Fi) allows voice calls to be routed over a Wi-Fi connection using IMS, useful in areas with poor cellular coverage. The call is handled by the same IMS core as VoLTE. VoWiFi requires operator activation and device support.

VoLTE compatibility depends on three factors: (1) the operator must have VoLTE enabled on their network, (2) your device must support IMS and be whitelisted by the operator, and (3) the device must support at least one LTE band deployed by the operator. Even if a device supports VoLTE in general, operators maintain whitelists of approved devices.

AMR-WB (Adaptive Multi-Rate Wideband) is the standard HD voice codec for VoLTE, defined in 3GPP TS 26.190. EVS (Enhanced Voice Services, TS 26.441) is a newer codec that provides super-wideband or fullband audio quality, better handling of background noise, and improved performance at low bitrates. EVS is increasingly deployed alongside AMR-WB.

When a 5G device needs to make a voice call but the network doesn't support VoNR, the device falls back to 4G LTE to use VoLTE. This mechanism is called EPS Fallback (3GPP TS 23.502). The call setup takes slightly longer due to the inter-RAT handover from NR to LTE.