Wideband Audio usually refers to calls that utilize the G.722 audio encoding prodocol. G.722 is a wideband codec with more natural sound, better clarity, and superior intelligibility. You may have seen this when making Mobile calls, and you will occasionally get a 'HD' image, and the audio will sound much better. Historically, most phone calls have been made using the legacy G.711 audio protocol.
As you can see, G.722 has more than twice the audio capacity of standard telephony, and is well on its way to CD quality ('Super Wideband'). At AussieVoIP, we prioritise Wideband Audio over any other audio transmission, so if it's possible for you to get High Quality Audio, you will!