If you have ever noticed that some calls sound remarkably clear while others sound like you are talking through a tin can, the difference is usually VoLTE. Traditional 3G calls use the AMR-NB (Narrowband) codec, which captures frequencies from 300 Hz to 3.4 kHz. VoLTE uses AMR-WB (Wideband), capturing 50 Hz to 7 kHz — more than double the frequency range.