This revised Recommendation provides audio performance requirements for wideband audio (7 kHz) handset telephones. Associated test methods for verifying wideband audio performance are contained in Annex A. Requirements and test methods are specified for the major audio transmission parameters affecting wideband audio, including levels, frequency response, noise, distortion, spurious signals, sidetone, echo path and delay. Wideband audio represents a considerable departure from traditional telephony, offering significantly improved quality. The main revision encompassed by this version of the Recommendation is to adopt the wideband loudness rating algorithm as in Annex G/P.79.