ITU-T Recommendation P.79 describes the preferred method for calculating loudness ratings mainly in the case of local telephone systems which transmit a band of frequencies not exceeding about 180-4500 Hz. The purpose of using loudness ratings for telephone sets is two-fold: first, to provide the transmission planner with an adequate measure of how the sets perform in the network; second, to enable valid and unambiguous comparison between sets. Therefore, to avoid confusion, this version of this Recommendation contains only those telephone set loudness ratings which are of interest for these purposes. The current revision of ITU-T Recommendation P.79 is intended to clarify the application fields for Annexes A and G. This Recommendation incorporates in Annex A the description of narrow-band loudness ratings which is applicable for narrow-band and dual-mode narrow-band/wideband end-to-end transmission, including terminals. Annex G is intended to apply only for end-to-end wide-band transmission (100 Hz to 7 kHz) between wideband terminals.