The generic term used in the context of telephony is "wideband audio"
. The concept refers to audio transmission and reproduction that includes a wider range of audio frequencies than the legacy narrowband methods, as originally implemented on the Bell System POTS network (analog or, typically, G.711/G.729 audio).
In the context of VoIP telephony, "HD Voice" is a marketing term that indicates the use of a wideband audio CODEC for Voice over LTE, or VoLTE or business VoIP phone equipment. At this time, VoLTE primarily uses the AMR-WB (G722.2) audio CODEC
, whereas fixed VoIP equipment typically uses the Opus (RFC 6716) CODEC
or variants of the G.722 CODEC.
Polycom was one of the first vendors to use the term, to describe the audio capability of their IP audio conferencing products.
Compare this to the US high-definition TV, or HDTV standard: an easy-to understand term, described by the ATSC, for a system of audio and video transmission, that supports higher video resolution and wider-range audio reproduction.