VoLTE (Voice over LTE) is the technology US carriers use to deliver voice calls over their 4G LTE data networks. Before VoLTE, voice traffic ran on legacy circuit-switched 2G/3G networks while data ran on LTE; VoLTE unified them by running voice as a packetized service on LTE.
VoLTE delivers HD voice using wideband codecs — AMR-WB (Adaptive Multi-Rate Wideband, ~50–7000 Hz) and EVS (Enhanced Voice Services, ~50–14400 Hz). These codecs reproduce voice with significantly more clarity than the narrowband G.711 codec used in legacy phone networks and most VoIP services.
VoLTE adoption finished across major US carriers by 2025; the 3G shutdown that started in 2021–2022 was completed industry-wide. Today, every US cellular voice call is VoLTE. This matters for business eSIM products because cellular-grade VoLTE quality is now universal — five years ago it wasn't.