Fulcrum Systems supplies Yealink and Grandstream phones that feature HD Voice (High Definition Voice Quality), also called Wideband audio. HD extends the range of audio signals compared to traditional telephones. The range of the human voice extends from 80 Hz to 14 kHz. Traditional telephones limit audio frequencies to the range of 300 Hz to 3.4 kHz. HD transmits in the audio frequency range of 50 Hz to 7 kHz or higher. The result of the wider frequency range means less of a ‘telephone’ sound.